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 to be secured with a cotter pin passed through a hole in the bolt shank. This mechanical locking mechanism prevents the nut from backing off due to vibration, which is a mandatory safety requirement for critical rotating machinery and engine room equipment under USCG maintenance standards.