Far-Infrared Telescopes Have to Be Cooled,but Visible-Light Telescopes Do Not

Multiple Choice

Far-infrared telescopes have to be cooled,but visible-light telescopes do not.Why not?

A) Far-infrared radiation is absorbed by the Earth's atmosphere.
B) Visible-light telescopes detect light from cool objects.
C) Far-infrared telescopes can only work in space.
D) Telescopes are not hot enough to emit visible light.