clouds of hot gas large numbers of stars high energy compounds extremely reflective ice particles
I gave my students this multiple choice question: The Milky Way Galaxy is visible as a bright region in the night sky. Modern telescopic observation has made it possible to discover that the brightness of the Milky Way Galaxy is due primarily to which structure?

Only one answer is correct among these 4 choices:
- clouds of hot gas
- large numbers of stars
- high energy compounds
- extremely reflective ice particles

Could you tell me which one is correct?

large numbers of stars