Which Statement Is Correct

Which statement is correct?

A) Keynesian economics is unrelated to the events of the Great Depression.
B) Classical economics approaches the economy as three separate but interrelated sectors, while Keynesian economics looks at the economy as a whole.
C) Keynesian economics was developed by the Scholastic School at Salamanca in the late medieval period.
D) The classical school of economics was developed during the classical age of Greece.