The Sun Is A Star
a) This phenomenon proves the fact that the sun rotates in the direction from point A to B. In other words, as viewed from the top, the sun rotates counter-clockwise.
b) The light from point A shows a Doppler blueshift effect, and the light from point B shows a redshift effect.
c) The magnitude of the increase or decrease in frequency by the Doppler effect at point C is greater than that at point B.