Question 235General Subjects - QMED

The correct answer is B) Castellated nut. Castellated nuts are the best choice when it is important that a nut does not work itself loose due to vibration. This is because castellated nuts have slots cut into the top of the nut that allow a cotter pin or split pin to be inserted through the nut and bolt, effectively locking the nut in place and preventing it from backing off. The other options, such as cap nuts, wing nuts, and square nuts, do not have this vibration-resistant locking feature, making them less suitable for applications where the nut must remain securely tightened.