to measure the density of Earth's atmosphere. to learn more about stars and planets. to observe the surface of the Moon. to better understand Earth.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: A telescope would be used for all the following except
Possibilities:
- to measure the density of Earth's atmosphere.
- to learn more about stars and planets.
- to observe the surface of the Moon.
- to better understand Earth.

to measure the density of Earth's atmosphere.