periodic dimming of the stars periodic X-ray bursts from the stars rapid location changes of the stars regular spectrum changes from the stars
I gave my students this multiple choice question: Which observation provides evidence of the existence of planets orbiting other stars?

Only one answer is correct among these 4 choices:
- periodic dimming of the stars
- periodic X-ray bursts from the stars
- rapid location changes of the stars
- regular spectrum changes from the stars

Could you tell me which one is correct?

periodic dimming of the stars