Questions 5 and 6Choose the appropriate letters A-D and write them in boxes 5 and 6 on you

Questions 5 and 6

Choose the appropriate letters A-D and write them in boxes 5 and 6 on your answer sheet.

The greatest outcome of the discovery of the reaction principle was that

A．rockets could be propelled into the air.

B．space travel became a reality.

C．a major problem had been solved.

D．bigger rockets were able to be built.