radio wave emissions a wobble in the rotation of the star regular occurring eclipses of its moons the discovery of a star as large as our own
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Planets outside of our solar system have been detected. What suggested the presence of a planet outside of our solar system?
Possibilities:
- radio wave emissions
- a wobble in the rotation of the star
- regular occurring eclipses of its moons
- the discovery of a star as large as our own

a wobble in the rotation of the star