What Is the Distribution of Stars in the Spiral Arms

Multiple Choice

What is the distribution of stars in the spiral arms of a typical spiral galaxy?

A) The density of stars in the arms is far higher than the density of stars between the arms.
B) Far fewer but brighter stars exist in the arms, while many more fainter stars exist between the arms.
C) All the stars of a spiral galaxy are in the arms; there are none at all between the arms.
D) The density of stars is relatively uniform in the disk of the galaxy but is slightly higher within the arms than between them.