X-Ray Observations Indicate That Around the Milky Way There May

X-ray observations indicate that around the Milky Way there may be an extended halo of

A) hot and diffuse gas at 2 million K, similar to that in the solar corona.
B) cold and dense gas where new stars form abundantly.
C) cosmic rays captured from other galaxies.
D) ions accelerated by strong magnetic fields.
E) gas heated by the very active supermassive black hole at the center.