The correct answer is<span>b. that Germany was researching nuclear weapons
The letter explained how Germany was working on a nuclear program and it urged the United States to also start working on one to prevent Germany from using it. This is one of the reason why when the US joined the war they started saving scientists from Nazis and sending them to the United States and using their knowledge.</span>
"<span>b. that Germany was researching nuclear weapons" is the best answer from the list of options</span>, but it should be noted that the letter was more of warning that nuclear bombs were a possibility.
