Answer:
Oil embargo.
Step-by-step explanation:
The events that led Japan to launch an attack at the United States base at Pearl Harbor were not just because of a single cause. It was a number of events that had accumulated and exploded after the US decided to ban all oil exports to foreign nations.
Japan had been slowly expanding its authority to nations including China. The increase in Japan's power led the US to embargo all oil exports which left Japan with a minimal oil resource. This prompted the Japanese nation to attack the US base at Pearl Harbor.
Thus, the correct answer is the first option.