Japan exercised its newfound military might when it invaded
a. manchuria
b. china
c. korea
d. russia

The correct answer is:

A. Manchuria

"The Japanese invasion of Manchuria began on 19 September 1931, when the Kwantung Army of the Empire of Japan invaded Manchuria immediately following the Mukden Incident . After the war, the Japanese established the puppet state of Manchukuo. Their occupation lasted until the Soviet Union and Mongolia launched the Manchurian Strategic Offensive Operation in 1945."

the answer is d.index