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