Which statements about Albert Einstein are true?

Select all correct answers.

His formula E=mc² led scientists to understand that splitting a uranium atom resulted in the release of extraordinary amounts of energy.

He left Germany, never to return, and became an American citizen.

He led the Manhattan Project, a program to create and test the atomic bomb.

He wrote to Franklin Roosevelt, urging that the United States start working to build an atomic bomb before the Germans could do so.