Which of the Following Statements About Thermal Electrocyclic Reactions Is $\sigma$

Which of the following statements about thermal electrocyclic reactions is not true?

A) The number of $\sigma$ bonds in the conjugated polyene determines whether rotation is conrotatory or disrotatory.
B) Thermal electrocyclic reactions occur in a disrotatory fashion for a conjugated polyene with an odd number of $\pi$ bonds.
C) Thermal electrocyclic reactions occur in a conrotatory fashion for a conjugated polyene with an even number of $\pi$ bonds.
D) In thermal reactions, we consider the orbitals of the HOMO of the ground state electronic configuration to determine the course of the reaction.