taking warning from near vehicle at night

Which of the following is true of the driver of the vehicle that takes the warning of the near of the vehicle at night?

1- Signal late signaling to the vehicle driver in the rear

2- Keeping the speed constant, slowing if necessary

3- Turning on the indicating lamps

4-  Approaching the left of the vehicle road


The right answer is:  2- Keeping the speed constant, slowing if necessary