In which case are you not allowed to overtake behind another vehicle that is already overtaking?
A)Overtaking is never allowed when another vehicle is already overtaking.
B)When traveling on a roundabout.
C)When you do not have sufficient visibility of the road ahead.Correct
# Explanation: Chained overtaking
You cannot overtake behind another vehicle that is already overtaking when **you do not have sufficient visibility of the road ahead**. This is essential for your safety, as you need to clearly see whether an oncoming vehicle is approaching before beginning the overtaking maneuver. Without this visibility, the risk of head-on collision is very high.