a black hole a galaxy a nebula a solar system
I am hesitating between 4 options to answer the following question, which option should I choose?
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?
Possibilities:
- a black hole
- a galaxy
- a nebula
- a solar system

a galaxy