Final answer:
Lift is the force that provides the centripetal acceleration necessary for an airplane to fly in a horizontal circle, allowing it to maintain its circular path.
Step-by-step explanation:
The force that provides the centripetal acceleration necessary for circular motion in an airplane is lift. When an airplane is flying in a horizontal circle, it requires a force that points towards the center of the circle to maintain its circular path. This force is none other than the lift generated by the wings of the airplane. Lift acts perpendicular to the relative airflow and supports the airplane against gravity. In the context of horizontal circular motion, the component of lift that points towards the center of the circle acts as the centripetal force necessary to change the direction of the airplane's velocity without altering its magnitude, thereby enabling circular motion.
It is important to note that although thrust propels the airplane forward, gravity pulls it towards the ground, and tension can be a centripetal force in scenarios such as tetherball, these forces do not provide the centripetal force in this case. The correct answer is C. Lift.