When did japan surrender?
a. after the first atomic bomb was dropped
b. the day the soviet union invaded manchuria
c. the day after germany and italy surrendered
d. a few days after the second atomic bomb was droppe

The correct answer is D.
 
On August 6 1945, the U.S. dropped the first atomic bomb on Hiroshima  and three days later, a second one on Nagasaki. On August 15 1945, the surrender of the Empire of Japan was announced by Imperial Japan and was officially signed on September 2 1945 bringing the second world war to a close.
 The Soviets had declared war on Japan on the 8th of August just before  Nagasaki was bombed. This plus the dropping of the atomic bombs put Japan in a hopeless position to continue fighting and she was thus forced to surrender, and that unconditionally.