Which of the Following Statements About the Claisen Rearrangement Is

Which of the following statements about the Claisen rearrangement is true?

A) The Claisen rearrangement occurs readily in a suprafacial pathway under photochemical conditions.
B) The Claisen rearrangement involves three electron pairs; two inp bonds and one in as bond.
C) The Claisen rearrangement occurs readily in an antarafacial pathway under thermal conditions.
D) The Claisen rearrangement involves the rearrangement of an unsaturated ether to a b,g-unsaturated carbonyl compound.