Which statements are correct for non-collinear or circular Doppler-motion situations in the classical approximation?

Select all that apply

• Option A

  At an instant, only radial velocity contributes to the usual first-order Doppler shift.

• Option B

  A source moving exactly transverse to the source-observer line has zero instantaneous radial Doppler shift.

• Option C

  A source moving in a circle centred on a stationary observer produces no classical Doppler shift at that observer.

• Option D

  For a far-away observer viewing a circularly moving source, maximum and minimum frequencies occur near maximum approach and recession radial speeds.