How parliament can enact or repeal any law it pleases, in spite of 'basic structure'? answer given is D

the question is not asked in context of Indian Parliament but in context of a political system where Parliament is sovereign like in  Britain.

This is in fact a wonderful question to get wrong. Any hastened reading of the question is likely to get you a wrong output. This must be a PYQ from CSE or CDS or CAPF!! It is a nearly impossible question to frame otherwise.