Which of the Following Statements About Electrocyclic Ring Closure Is $\sigma$

Which of the following statements about electrocyclic ring closure is not true?

A) It is an intramolecular reaction.
B) It requires heat or light.
C) The cyclic product contains one more $\sigma$ bond and one fewer $\pi$ bond than the reactants.
D) The cyclic product contains one more $\pi$ bond and one fewer $\sigma$ bond than the reactants.