Why Was the Battle of Britain a Serious Mistake by Hitler

Why was the Battle of Britain a serious mistake by Hitler?

A) The English not only resisted the attacks,but became more united against the Nazis.
B) The resources Hitler wasted attacking Britain delayed his attack on Russia for more than a year.
C) British resistance so impressed Americans that the United States declared war on Germany.
D) After Churchill was forced to resign,Atlee became Prime Minister and inspired England to resist.
E) The Luftwaffe was destroyed,leaving Germany open to Allied bomber attacks.