Which of the following would NOT cause an inoperative starter?

An inoperative starter can result from various issues, but the choice involving worn or missing flywheel ring gear teeth does not directly prevent the starter from functioning. When the starter motor is engaged, it connects with the flywheel or flexplate through a starter drive, which is designed to mesh with the ring gear teeth. If some teeth are missing or worn, there might be intermittent engagement or grinding noises, but the starter can still attempt to engage. This means that the starter can technically operate even if it struggles to turn the engine over due to the compromised teeth on the flywheel.

In contrast, options that involve the neutral safety switch, open circuits, or grounding issues directly prevent the starter from getting the necessary signals or power to engage, rendering it inoperative. This ensures that the correct choice not only accurately reflects a technical understanding but also highlights how certain components interact within the starting system.