Question

what is space force?
a class that only the u.s. air force academy offers
the newest branch of the u.s. military
a club offered within the u.s. air force academy

Explanation:

The U.S. Space Force is indeed the newest branch of the U.S. military, established in 2019. It is not just a class or a club within the U.S. Air Force Academy.

Answer:

the newest branch of the U.S. military