Is it permitted to travel over a broken longitudinal road marking if you are on a carriageway with lanes less than 3 metres wide?

A)No, never.
B)Yes, always.
C)Yes, whenever necessary and traffic safety permits.Correct
As a general rule, you must keep to the right and, especially on bends and crests with limited visibility, as close as possible to the edge of the carriageway. If the lane is narrow — less than 3 metres — you may travel over the longitudinal marking if necessary and safety permits, keeping to the right when passing other vehicles.