A. Stay in the right-hand side of the lane
A. Stay in the right-hand side of the lane
B. Speed up
C. Stay in the middle of your lane as the left of the lane is more dangerous
D. Be prepared to slow down to ensure a safe passing manoeuvre
If you notice a vehicle ahead that the overtaking vehicle hasn't noticed, there's a potential problem. You could maintain your speed and that would mean the overtaking vehicle would have to brake, but at least they would be able to get in behind you more quickly.
If you brake and the other vehicle brakes, we can assume it will probably be at a similar pace and it would make it difficult for the other vehicle to pull to the left because your vehicle will still be in the way.
If you brake and the other vehicle doesn't then you will minimise the time required for it to overtake you and pull back in to the left-hand lane.
Ultimately, if an accident is going to occur and you could be involved in it, it's best for you to be going as slowly as possible.