What does an officer swinging a yellow light indicate?

What does an officer swinging a yellow light indicate?
A)Requires road users toward whom the officer directs the light to stop.Correct
B)Requires drivers approaching the officer to reduce speed.
C)Requires passing on the side indicated by the light.
An officer swinging a red or yellow light requires the road users toward whom the officer directs the light to stop.
If the officer were indicating that we should reduce speed, they would do so by moving their arm alternately up and down.