What component helps to reduce the risk of brake overheating?

Answer: C — Spring brakes

The component that helps to reduce the risk of brake overheating is the spring brakes. Spring brakes are a safety mechanism that serves to apply the brakes in case of an air loss in the braking system, which can happen if there's a failure. By ensuring that the brakes engage effectively in such situations, spring brakes help to prevent excessive heat buildup from prolonged or inadequate braking. Additionally, they provide an effective method for ensuring the vehicle remains stopped when it is parked, thereby reducing the chances of brake wear from heat generated during operation. On the other hand, brake fluid is primarily involved in transferring force in the braking system, while brake drums are a part of the braking system that can hold heat but do not directly prevent it. The vacuum assist system is more related to enhancing brake feel and effort rather than managing heat, making spring brakes the correct choice for addressing overheating risks.