The Galactic Halo Contains Outer and Inner Shells of Stars

The galactic halo contains outer and inner shells of stars. How does the outer shell compare to the inner shell?

A) The two shells are virtually identical except for their distance from the galactic nucleus.
B) The outer shell contains all of the globular clusters.
C) The inner shell contains all of the globular clusters
D) The stars of the outer shell are relatively metal-rich.