How does the following paragraph BEST support a main idea of the speech?

Before 1939, most scientists believedit could be possible to release energyfrom atoms. But no one knew anypractical way of doing it. By 1942,however, we knew that the Germanswere working very hard to find a way to add atomic energy to their other engines of war. They hoped to enslave the world with these weapons. But they failed. We may be grateful to God that the Germans got these weapons late. They only had a few of them, too We may be even more grateful that they did not get the atomic bomb at all.

A. It tells when scientists began to look for ways to develop an atomic bomb.

B. It explains why scientists worked quickly to develop an atomic bomb.

C. It describes how scientists felt about developing an atomic bomb

D. it shows what scientists understood about an atomic bomb