What is one component specifically designed to maintain the integrity of a starter’s operation?

The correct answer emphasizes the role of brushes in maintaining the integrity of a starter's operation. In electric starter systems, brushes are critical components that transfer electrical current to the rotating armature within the starter motor. They provide the necessary electrical connection needed for the motor to operate effectively. Proper functioning of the brushes ensures that the starter motor receives sufficient power to crank the engine, which is essential for initiating engine operation.

In contrast, while the commutator helps in switching the current in the motor to allow smooth rotation, and the solenoid is primarily responsible for engaging the starter gear with the engine flywheel, these components do not directly maintain the ongoing operation of the starter like the brushes do. Similarly, the gearbox plays a role in transmitting power but does not handle the electrical integrity essential for the starter's performance. Thus, the brushes are specifically designed for this function, highlighting their importance in ensuring the starter performs correctly.