听力原文：A 23-day search operation that begins Thursday will include 84 Americans and thei

听力原文： A 23-day search operation that begins Thursday will include 84 Americans and their Vietnamese counterparts split in the eight teams. The spokesman for the operation said four of the teams are currently in the midst of a dry season. The spokesman said Vietnam turned over 67 sets of remains which the Vietnamese believed to be of Americans last year, the most since it began returning such remains in the early 1980s. Vietnam first allowed American search teams into the country in 1988 and the first consisted of just three men.

Vietnam has turned over hundreds of sets of remains since the end of the war in 1975. So far 280 such sets have been positively identified as the remains of missing Americans. The remains are examined by forensic specialists at the U.S. military laboratory in Hawaii.

The fates of more than 2,200 American servicemen who are missing in southeast Asia remain unsolved. 1,648 of those are listed as missing in Vietnam or its waters. In an interview with the Associated Press, Major General Thomas Needham, the search operation commander, said he was pleased with the process being made to account for the missing men. He said he and his teams were allowed to go wherever they wished in Vietnam. General Needham said he constantly pushed the Vietnamese to find and hand over more documents about the missing men.

General Needham said that he didn't believe the Vietnamese government was holding back remains. However, he said some individuals who had come across remains were holding them back in the hope of being paid for them. The U.S. does not pay for remains.

In the related development, the U.S.military announced Wednesday that Admiral Charles Lawson, the commander-in-chief of the Pacific, will visit Vietnam beginning January 16th. Admiral Lawson will visit the American Missing-in-Action Office in Hanoi, discuss the issue with the Vietnamese officials and travel south to observe the excavations. Admiral Lawson will become the highest ranking U. S. military officer to visit Vietnam since the end of the War. Admiral Lawson's visit and extensive search come at a time when officials in Washington say the question of the U. S. trade embargo against Vietnam is under active review.

Ann Butler for VOA news, Bangkok.

How many missing American servicemen have been positively confirmed dead in Vietnam so far？

A．67.

B．280.

C．84.

D．1648.