The Boeing B-29 was used by the United States Air Force towards the end of World War II, as well as in the Korean War. They were only produced from 1943-1946, right at the end of the war. However, they were used by the USAF and Royal Air Force until 1954. The entire line (including the revised version, the B-50) was retired in 1960.
Therefore, the answer is A, since production of the plane stopped in 1946, one year after the end of WWII.
