Question

final exam
why are otters considered a keystone species?
because they are a predator that keeps sea urchins in check which helps kelp forests thrive
because if they were wiped out, they would not be missed
because they are the prettiest and most lovable of all the sea mammals

Explanation:

Otters prey on sea urchins. Sea urchins over - graze kelp. By controlling sea urchin populations, otters allow kelp forests to flourish, playing a crucial role in the ecosystem.

Answer:

because they are a predator that keeps sea urchins in check which helps kelp forests thrive