Which of the following correctly lists the conformations of cis-1,4-di-t-butylcylcohexane in order of increasing energy?

A) chair < boat < twist boat < half-chair
B) twist boat < boat < chair < half-chair
C) chair < twist boat < half-chair < boat
D) boat < chair < twisted boat < half-chair
E) half-chair < chair < boat < twisted boat