Which of the Following Actions Were Meant by the Term

Which of the following actions were meant by the term blitzkrieg?

A) extensive aerial bombardment by the Allies followed by infantry invasion of Germany
B) the Nazi plan to strike western Europe before turning against the Soviet Union
C) tank-led assaults, followed by motorized infantrymen and finally foot soldiers
D) all-out assault on civilian populations who had helped the Nazis after the civilians were no longer useful