Why Would Astronomers Place an X-Ray Observatory in Space,like the Chandra

Multiple Choice

Why would astronomers place an X-ray observatory in space,like the Chandra observatory?

A) to map X-ray emissions from the moon
B) to map X-ray emissions from the sun
C) to record X-rays emitted from the big bang; the so called background radiation of the universe
D) to map deep X-ray emissions from deep space,particularly as a proxy for materials being sucked into black holes