The Famous Shapley-Curtis Debate in 1920 Concerned Which Fundamental Astronomical

The famous Shapley-Curtis debate in 1920 concerned which fundamental astronomical question in astronomy?

A) whether all stars were like the Sun or fundamentally different
B) whether the spiral "nebulae" were part of the Milky Way Galaxy or more distant, separate entities
C) whether the universe was expanding outward in all directions
D) whether the Sun was at the center of the Milky Way Galaxy