a black hole a galaxy a nebula a solar system
I gave my students this multiple choice question: In 2004 the Hubble space telescope captured images of distant star clusters, each containing about a million stars. These star clusters were most likely part of which structure?

Only one answer is correct among these 4 choices:
- a black hole
- a galaxy
- a nebula
- a solar system

Could you tell me which one is correct?

a galaxy