Correct!

You're travelling at the legal speed limit. What should you do if the vehicle behind approaches quickly, flashing its headlights?

Accelerate to make a gap behind you
Touch the brakes sharply to show your brake lights
Maintain your speed to prevent the vehicle from overtaking
Allow the vehicle to overtake
Correct answer

DVSA theory test explanation

Do not enforce the speed limit by blocking another vehicle's progress. This will only cause frustration. Allow the other vehicle to pass when you can do so safely.