On this interurban road it is mandatory to use dipped headlights...
A)only when high-beam lights are not available.
B)at all times.
C)when there is a possibility of dazzling other users.Correct
On this insufficiently lit interurban road we may use the high-beam lights, but we must mandatorily use the dipped headlights (short-range lights) whenever there is a possibility of dazzling other users of the same road or any other road, and especially drivers of vehicles travelling in the opposite direction.