Potential energy, I’m pretty sure I don’t know but we was learning this in science and this is all I remember that potential energy is the moment energy reaches to a stop...
I am not entirely sure but i believe the answer is C scupture
The gravitational force between two objects is given by:

where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the separation between the two objects
The distance of the telescope from the Earth's center is

, the gravitational force is

and the mass of the Earth is

, therefore we can rearrange the previous equation to find m2, the mass of the telescope: