What must we do in view of the sign?

A)Turn off the low-beam lights.
B)Mandatorily use the low-beam or high-beam lights.
C)Keep the dipped beam lights on if visibility circumstances so require.Correct
This sign indicates the end of the obligation to use low-beam lights imposed by a previous sign.
In any case, if visibility circumstances so require, for example at night, we must keep the lights on.
In any case, if visibility circumstances so require, for example at night, we must keep the lights on.