According to the passage, one reason that the authors gave rats carbohydrates was toA．depr

f a rat varies with the

A．amount of protein present in a meal.

B．concentration of serotonin in the brain before a meal.

C．concentration of leucine in the blood rather than on the concentration of tyrosine in the blood after a meal.

D．concentration of tryptophan in the brain before a meal.

E．number of serotonin-containing neurons present in the brain before a meal.

try?

A．It displaced fewer skilled workers than R/P automation did.

B．It could have been implemented either by experienced machinists or by computer engineers.

C．It was designed without the active involvement skilled machinists.

D．It was more difficult to design than R/P automation was.

E．It was technically superior to R/P automation.

ntage goals set by "some federal and local agencies "(line 18)are

A．more popular with large corporations.

B．more specific.

C．less controversial.

D．less expensive to enforce.

E．easier to comply with.

s result quickly in orders might cause it to

A．experience frustration but not serious financial harm.

B．face potentially crippling fixed expenses.

C．have to record its efforts on forms filed with the government.

D．increase its spending with minority subcontractors.

E．revise its procedure for making bids for federal contracts and subcontracts.

hree kinds of "talk" therapy(Freudian, Rogerian, and cognitive)and also behavior. therapy. Since the periods when I was in therapy were the least happy times of my life, I have concluded that psychotherapy cannot work for me. Which of the following statements, if true, would most weaken Johns conclusion?

A．Behavior. therapy is designed to address different problems from those addressed by "talk" therapies.

B．The techniques used in behavior. therapy are quite different from those used in "talk" therapies.

C．People who try several different types of psychotherapy tend to be happier than people who try only one type of psychotherapy.

D．People who try several different types of psychotherapy are more likely to find one that works for them than are people who try only one type of psychotherapy.

E．People undergoing psychotherapy that ultimately works are often unhappy while they are in therapy.

thesis that colds are, at least sometimes, caused by becoming chilled; it is the chill that allows a rhino virus, if present, to infect a person. Which of the following, if true, most seriously weakens the force of the evidence cited above?

A．Being chilled is a form. of stress, and stress lowers the defenses of a person" s immune system, which guards against infection.

B．After a rhino virus has incubated in a person for several days, the first symptom it causes is a feeling of chilliness.

C．People who are tired and then become chilled are more likely to catch severe colds than are people who are chilled without being tired.

D．Some people who catch colds are not sure what it was that allowed them to catch cold.

E．Rhino viruses are not always present in the environment, and so a person could become chilled without catching a cold.

t followed thirty only children and thirty-five first-born children to the age of three found that the two groups of children behaved very similarly to each other toward their peers, their parents, and other adults. Which of the following, if true, most weakens the conclusion drawn above?

A．The groups being compared did not contain the same number of children.

B．More time was spent observing the interactions of children with their mothers than with their fathers.

C．Most of the researchers involved in the study were persons who had no brothers or sisters.

D．The first-born children were, on the average, nearly three when their parents had the second children.

E．The "other adults" described in the study consisted mainly of members of the research team.

were found more likely than other sedentary middle-aged men to have a high blood level of cholesterol, which is a factor increasing risk of heart disease. Cholesterol can reach the blood from food and drink but is not contained in coffee. Which of the following, if true, most seriously weakens a conclusion from the study that for sedentary middle-aged men coffee increases the risk of heart attack?

A．A sedentary style. of life increases levels of cholesterol in the blood.

B．Coffee contains caffeine, which acts as a stimulant that increases heart rate.

C．The men studied drank their coffee without milk or cream, which contain cholesterol.

D．In both groups, the men were likely to be overweight, and excess weight is a factor that increases risk of heart diseases.

E．The men who drank more than two cups of coffee a day also ate more foods high in cholesterol.

antly in a rural county this year, as compared to last year, health officials attribute this decrease entirely to improved sanitary conditions at water-treatment plants, which made for cleaner water this year and thus reduced the incidence of the disease. Which of the following, if true, would most seriously weaken the health officials explanation for the lower incidence of the disease?

A．Many new water-treatment plants have been built in the last five years in the rural county.

B．Bottled spring water has not been consumed in significantly different quantities by people diagnosed as having the intestinal disease, as compared to people who did not contract the disease.

C．Because of a new diagnostic technique, many people who until this year would have been diagnosed as having the intestinal disease are now correctly diagnosed as suffering from intestinal ulcers.

D．Because of medical advances this year, far fewer people who contract the intestinal disease will develop severe cases of the disease.

E．The water in the rural county was brought up to the sanitary standards of the water in neighboring counties ten years ago.

es account for forty percent of the cost of manufacturing gauges at both Shelby Industries and Jones Industries. Shelby Industries is seeking a competitive advantage over Jones Industries. Therefore, to promote this end, Shelby Industries should lower employee wages. Which of the following, if true, would most weaken the argument above?

A．Because they make a small number of precision instruments, gauge manufacturers cannot receive volume discounts on raw materials.

B．Lowering wages would reduce the quality of employee work, and this reduced quality would lead to lowered sales.

C．Jones Industries has taken away twenty percent of Shelby Industries business over the last year.

D．Shelby Industries pays its employees, on average, ten percent more than does Jones Industries.

E．Many people who work for manufacturing plants live in areas in which the manufacturing plant they work for is the only industry.