Which of the following types of nuts would be best suited to use when it is important that a nut not work itself loose due to vibration?

Correct Answer: Option B — Castellated nut

Castellated nuts are designed with slots that align with a hole in the bolt, allowing a cotter pin to be inserted. This mechanical locking mechanism prevents the nut from backing off due to vibration, which is a critical safety requirement for rotating machinery and high-vibration engine room equipment.