What safety distance shall we leave from the vehicle ahead of us in a tunnel?

A)150 metres, if the vehicle ahead is a truck of more than 3,500 kg.
B)At least 100 metres, whatever vehicle is travelling ahead of us.Correct
C)At least 50 metres.
In tunnels or underpasses, when not intending to overtake, a safety distance of at least 100 metres or a minimum time interval of four seconds must be maintained at all times from the preceding vehicle.
For vehicles with a MAM exceeding 3,500 kg, the safety distance must be at least 150 metres or a minimum interval of 6 seconds.
The following sign reminds us of the general safety distance we must keep.
For vehicles with a MAM exceeding 3,500 kg, the safety distance must be at least 150 metres or a minimum interval of 6 seconds.
The following sign reminds us of the general safety distance we must keep.