Why did the communists and nationalists stop fighting a civil war in china in 1937?

uring the Second Sino-Japanese War (1937–45), China was effectively divided into three regions—Nationalist China under control of the government, Communist China, and the areas occupied by Japan. Each was essentially pitted against the other two, although Chinese military forces were ostensibly allied under the banner of the United Front. By the time Japan accepted the surrender terms of the Potsdam Declaration on August 14, 1945, China had endured decades of Japanese occupation and eight years of brutal warfare. Millions had perished in combat, and many millions more had died as a result of starvation or disease. The end of World War II did not mark the end of conflict in China, however.

Explanation:

they gained popular support by speaking out against communists

in the united states. ( d.)

d is the best answer for this question.