Which best describes the Cold War during the years when Nikita Khrushchev led the Soviet Union? O Cold War tensions were relaxed because Khrushchev was a dedicated reformer.
O Cold War tensions were at their height, especially after Khrushchev ordered an end to Leonid Brezhnev's
domestic reforms.
O Cold War tensions were relaxed because Khrushchev ordered that the Berlin Wall be destroyed.
O Cold War tensions were at their height, especially because of the Cuban Missile Crisis.

The last one, tensions were at their height, is the correct one. This is because Khrushchev was the one who allowed the missiles into Cuba as retaliation for American missiles in Turkey, and led when the crisis occurred.

Here are why the other ones are incorrect;

1. Khrushchev was not the most dedicated reformer, that would go more to Gorbachev, whose reforms gave the Soviet citizens more freedom, allowed for more liberalization of the economy, and arguably led to the downfall of the USSR.

2. Brezhnev was actually the leader after Khrushchev, so he couldn’t have made reforms yet.

3. The Berlin Wall was torn down in 1989, way after Khrushchev’s ruling in the USSR (and also was torn down by the people).

Hope this helps!