Answer:
b. RED
Step-by-step explanation:
As we know that traffic signals are used to control the movement of traffic so that it is controlled.
Now we know that there must be a specific signal that people will know so that traffic must be controlled.
Here different colors have specific meaning which is given as
RED : Stop at the signal
YELLOW : Slow down or ready to move
GREEN : You can move the vehicle
so here as per this signal rule we can say that RED color signal means the driver has to stop at the stop line