Which event pushed the western allies to seek a military alliance? the successful detonation of the soviet union’s first atomic bomb the refusal of soviet union to accept financial aid under the marshall plan the communist takeover of the czech government with soviet support the complete demilitarization of east germany by the soviet union

The correct answer should be

the communist takeover of the Czech government with Soviet support

A democratic Czech government was overthrown by communists who had soviet support and other European countries believed that similar could happen to them which is why they decided to make an alliance. Soviets were getting stronger and Europe was still not as well connected as them.