Which of the following compounds of optically inactive

Which of the following compound is optically inactive ?

Which of the following compounds is optically inactive?

Which of the following compounds are optically inactive but exhibits geometrical isomerism?

Presence of chiral center is not an essential condition to show optical isomerism. Essential condition is, compound should show non-superimposable mirror image. Allenes do not contain chiral center but show optical isomerism when different groups are attached on double bonded carbons. Biphenyls also show optical isomerism when both rings are perpendicular to each other and any ring should not contain plane of symmetry. Which of the following compounds is optically inactive?