You are at the aquarium looking at a freshwater mammal tank and an adult manatee swims close to the glass. On his front flippers you see fingernails. What is a likely explanation for the presence of fingernails on a manatee?

a. They are analogous to human (ngernails.

b. They are a developmental homology.

c. They are analogous to bear claws.

d. They are homologous to fish fins.

e. They are vestigial structures.