Answer:
The correct answer is B. The United States did not complain about the construction of the Berlin Wall in 1961 because it protected West Berlin from any attempts of the Soviet Union to conquer it.
Step-by-step explanation:
The American reaction to the construction of the wall was slow: 20 hours passed until the appearance of the military forces on the border; 40 hours until they communicated with the Soviet commander of Berlin; and 72 hours until they protested at Moscow's diplomacy. There were more and more rumors that the Soviets had assured the Western allies that they would not threaten their rights. The experience of the blockade had shown the allies that West Berlin was threatened, so the construction of the wall was a material confirmation of the status quo, that is, the recognition of Western domination of that part of the city. The Soviet Union abandoned its request that West Berlin be "free" of allied troops, which it had formulated in the Khrushchev ultimatum of 1958. In this way, the United States ensured that the Soviet Union would not attack West Berlin.