In 1939, who wrote a letter to president roosevelt alerting him to "a new and important source of energy" developed by scientist in the united states? a. winston churchill b. albert einstein c. josef stalin d. harry truman

That is an easy question. Albert Einstein is the only scientist among those in the options. Winston Churchill was the Prime Minister of Great Britain, Josef Stalin was the Grand Premier of the Soviet Union, and Harry Truman was the President of the United States of America.

That leaves Albert Einstein, a Jewish scientist and refugee of WWII from Germany.