There Are No X-Ray Telescopes on Earth Because

Multiple Choice

There are no X-ray telescopes on Earth because:

A) they are too expensive to build.
B) no one has yet invented an X-ray telescope that works.
C) we can't figure out how to direct an X-ray beam through space.
D) X-rays don't penetrate Earth's atmosphere.
E) there are no astronomical objects that emit X-rays.