Fish : Scales :: Bird : ? Pick the option that completes the analogy.

The relation is a creature : the covering spread over its whole body. Scales sheathe a fish; feathers sheathe a bird. The three distractors are all parts of a bird, which is what makes them inviting, but a beak, a pair of wings and a set of claws each sit at one place on the body — none of them clothes it the way scales clothe a fish.