Technician A says that a defective solenoid can cause a starter whine. Technician B says that a defective starter drive can cause a starter whining noise. Which technician is correct?

A defective starter drive can indeed be responsible for a whining noise during the operation of the starter. The starter drive, also known as the starter bendix or pinion gear, is the component that engages with the engine flywheel to crank the engine. If this part is malfunctioning—such as being worn out or improperly aligned—it may not engage correctly, leading to a situation where it spins without properly engaging, resulting in a characteristic whining sound.

On the other hand, while a defective solenoid can cause issues with the starter's operation, it is not typically known for producing a whining noise. Instead, the solenoid is responsible for activating the starter motor and engaging the drive with the flywheel. If it fails, you might experience various symptoms like a clicking sound or the starter not functioning at all, but a whining noise is more directly associated with problems related to the starter drive.

Therefore, the correct assessment is that Technician B is correct in suggesting that a defective starter drive can lead to a whining noise from the starter.