To achieve the anti-periplanar geometry for E2 reaction, the groups those are to be eliminated form a six-membered ring must be trans di axial .

It must be kept in mind that two substituents, which are trans to each other on two consecutive carbons of a cyclohexane ring can occupy axial positions on a chair conformation.

While flipping the chair conformation, the axial substituent becomes equitorial.

Answer the following questions on the basis of above write up: