What Two Events That Took Place in 1949 Led to Communist

Multiple Choice

What two events that took place in 1949 led to Communist gains during the Cold War?

A) creation of the Warsaw Pact and the failed anti-Communist revolution in Hungary
B) North Korea's invasion of South Korea and the Sino-Soviet Treaty between China and the USSR
C) the Communist-led coup in Czechoslovakia and the Soviet blockade of Berlin
D) Soviet acquisition of an atomic bomb and the Communists' takeover of China