Which type of muscle could act as an antagonist to an abductor?

An antagonist is a muscle that opposes the action of another muscle. In this case, considering the action of an abductor, which is a muscle that moves a limb away from the midline of the body, the opposing action would be to bring the limb back towards the midline.

The adductor muscle group specifically functions to draw body parts towards the center line of the body. This makes it the perfect antagonist to the abductor, as it directly opposes the abductor's action. By contracting, the adductor will counteract the pull of the abductor, effectively bringing the limb back toward the midline.

On the other hand, the rotator muscles typically assist in rotating a body part rather than providing a direct opposition to the abduction movement. The extensor and flexor muscles are primarily involved in movements related to straightening and bending joints, respectively, and do not directly counter the action of abduction. This delineates why the adductor is the most suitable choice when identifying an antagonist to an abductor.