Our Galaxy Is Suspected to Be Surrounded by a Galactic

Multiple Choice

Our galaxy is suspected to be surrounded by a galactic halo or corona because the disk of the galaxy

A) rotates faster than expected in its outer region.
B) rotates more slowly than expected in its outer region.
C) is only visible during a total eclipse of our Sun.
D) is surrounded above, below, and well beyond by the brightly glowing corona.