Why seals and sea lions would not be considered fish.

The word 'pinniped' means 'fin foot', as the four legs of seals, sea-lions and walrus have developed into flippers to better suit their life in the water. They are not fish! Even though a great part of their life is spent in the sea, pinnipeds are warm blooded air-breathing mammals known as marine mammals.

Explanation:

Sea lions (left) are brown, bark loudly, "walk" on land using their large flippers and have visible ear flaps. Seals have small flippers, wriggle on their bellies on land, and lack visible ear flaps. ... Both seals and sea lions, together with the walrus, are pinnipeds, which means "fin footed" in Latin.

a is the correct answer