Which of the following helped Japan's economy recover following World War II?

A.
Soviet humanitarian and military aid

B.
the discovery of oil and coal reserves

C.
significant investment by the United States

D.
the economic programs of the Marshall Plan

C. significant investment by the United States

C. significant investment by the United States

The correct answer is C. significant investment by the United States.

To arrive at this answer, we can eliminate options A and B because they are not accurate in the context of Japan's recovery after World War II. Option A suggests Soviet humanitarian and military aid, but Japan did not receive any significant aid from the Soviet Union. Option B mentions the discovery of oil and coal reserves, but the recovery of Japan's economy was not primarily driven by the discovery of these resources.

Now, let's focus on options C and D. Option D refers to the economic programs of the Marshall Plan, which was a United States initiative to help rebuild Western Europe after the war. However, contrary to popular belief, Japan did not receive direct assistance from the Marshall Plan. Therefore, option D can be ruled out.

This leaves us with option C, which states that significant investment by the United States helped Japan's economy recover. This is the correct answer. The United States did provide substantial economic assistance to Japan through the Dodge Line, the Dodge Plan, and other programs in the late 1940s and 1950s. These investments played a vital role in rebuilding Japan's industries, infrastructure, and trade, contributing to its rapid economic recovery and transformation into one of the world's leading economies.