You are driving with high beam headlights and approaching a vehicle traveling at a lower speed in the same direction; should you switch from high beam to low beam?

You are driving with high beam headlights and approaching a vehicle traveling at a lower speed in the same direction; should you switch from high beam to low beam?
A)No, as it is neither necessary nor advisable.
B)Only if you do not intend to overtake.
C)Yes, to avoid the possibility of dazzling through the rearview mirror.Correct