Which of the Following Statements About the Claisen Rearrangement Is $\pi$

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 $\pi$ bonds and one in a $\sigma$ bond.
D) The Claisen rearrangement involves the rearrangement of an unsaturated ether to a $\beta$ , $\gamma$ -unsaturated carbonyl compound.