When performing a static check to determine tooth contact, you should use which of the following compounds to coat the gear teeth?

Correct Answer: Option C — Prussian Blue.

Prussian Blue is a non-abrasive, high-viscosity pigment paste used to verify gear tooth contact patterns. When applied to the gear teeth, it transfers from the high spots to the mating surface during rotation, allowing the engineer to visually inspect and confirm proper load distribution across the tooth face.