In a tunnel with one lane in each direction, what is the minimum mandatory safety distance for passenger cars?

A)50 metres.
B)200 metres.
C)100 metres.Correct
When there is no intention 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 vehicle ahead.
For vehicles with a maximum authorised mass of more than 3,500 kg, the safety distance to be kept shall be at least 150 metres or a minimum interval of 6 seconds.
Remember that overtaking is prohibited in tunnels, unless there is more than one lane in your direction. In the case of this question, overtaking would not be permitted, so the safety distance cannot be reduced under any circumstances.
The following sign reminds us of the general safety distance we must maintain.
For vehicles with a maximum authorised mass of more than 3,500 kg, the safety distance to be kept shall be at least 150 metres or a minimum interval of 6 seconds.
Remember that overtaking is prohibited in tunnels, unless there is more than one lane in your direction. In the case of this question, overtaking would not be permitted, so the safety distance cannot be reduced under any circumstances.
The following sign reminds us of the general safety distance we must maintain.