What is common between whale, seal and shark?

The correct option is D Convergent evolution
In evolutionary biology, convergent evolution is the process whereby organisms not closely related, independently evolve similar traits as a result of having to adapt to similar environments or ecological niches. Convergent evolution creates analogous structures that have similar form or function, but that were not present in the last common ancestor of those groups. Whale, seal and sharks shows convergent evolution, as they have analogous structures used for swimming.

Therefore, the correct answer is option D.