Which of the following compounds would be optically inactive?  

An active ingredient is one that has no visible rotation. Carbon is tetravalent which means it can make four bonds. if four atoms are attached to carbon atoms as they are four different sites then carbon is called ACHIRAL CARBON. if there are atoms of molecules attached to the same carbon the carbon is called CHIRAL CARBON.

Molecules or atoms that revolve around a plane's flashlight illuminated by the clock or anticlockwise are called light beams.

Since an optically active alkane upon the other compounds gives an optically inactive alkaline.

when we rotate the half part of the amount the image looks like a mirror reflection hence the compounds are optically inactive.

Hence the correct option is (a),(b) and (d).