Answer:
Correct answer is through intelligence about the Soviet nuclear program .
Step-by-step explanation:
First two options are not correct of course because this led more to the strengthening of economy of United States, and was not pointed towards the Soviet Union.
Third option is not correct as this was related more to their space race that started during the 1950s.
Last option is correct as both countries were espionage each other which in some cases almost led to the war between two countries.