X-ray telescopes are located in orbit around the Earth because
A) X-ray telescopes on Earth would have to be too big.
B) X-ray telescopes are cheap and easy to launch into space.
C) there are too many X-ray telescopes on Earth, so now they are put in space.
D) X-rays don't reach the surface of Earth.
E) the X-rays that come out of the telescopes are dangerous to humans.
