What should a driver do to secure the towing vehicle before unhitching a trailer?

Apply the handbrake, switch off the ignition and engage a low gear.
Lower the jockey wheel and then switch off the ignition.
Disconnect the electrical supply to the trailer lights and lower the jockey wheel.
Apply the handbrake, lower the jockey wheel and switch off the engine.

Explantion: Before unhitching a trailer, apply the handbrake, switch off the ignition and engage a lower gear, so that the towing vehicle does not move while you are unhitching the trailer.

Theory Tester

What should a driver do to secure the towing vehicle before unhitching a trailer?

Managing Risk