Question

On July 16, 1945, President Truman issued the Potsdam Declaration. It warned Japan to surrender or face "utter and prompt destruction." Truman issued this warning shortly after A. Japan used its kamikaze attacks B. two atomic bombs were dropped on Japan C. the U.S. successfully tested an atomic bomb D. Japan attacked Pearl Harbor

Answer 1

Let's go through this one, too:

(A) is out because Japan had been using kamikaze attacks for awhile now, so they didn't prompt the Truman to suddenly issue this. (B) is also wrong because the US didn't drop the atomic bombs yet. (D) is very wrong because this was in 1945, almost four years after Japan attacked on December 7th, 1941.

So that leaves only one answer that makes sense: (C). The US tested the A-bomb about ten days before Truman made his declaration. IIRC, though, the date in the question is a little off...July 16th was the date for Trinity, but Truman made the actual Declaration on July 26th during the Potsdam Conference.