Which of the following led to increased tension between the united states and japan in 1937?
a. the nanjing massacre
b. roosevelt’s four freedoms speech
c. japan’s oil exports
d. the lend-lease act

The best choice would be A. The Nanjing Massacre led to the increased tension between the United States and Japan in the year 1937. This is because didn't like what the Japanese did in China and in other parts of Asia. The killings they made to many are not really favorable to the US.