How many years was it between japan's attack on china and pearl harbor document c?

10 years--Japan invaded Manchuria in 1931 and bombed Pearl Harbor in 1941. 

Japan began invasion of China in 1931 to gain access to resources in the iron rich Manchuria. This led to a 10 year push through China and the Southeast Asian countries until the Dec. 7th 1941 bombing of Pearl Harbor.