Given a statement, generate a question such that the answer is contained in that statement.

Smog is made up of carbon particles.
What is smog made up of?

detailed sight of stars requires a telescope
What type of telescope is required for detailed sight of stars?

at least two mirrors are used for observing stars by astronomers

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
How many mirrors are used for observing stars by astronomers?

