A Spiral Galaxy Is Observed Edge-On So That the Spiral

Multiple Choice

A spiral galaxy is observed edge-on so that the spiral arms cannot be seen clearly. Is it possible to classify this into one of the Sa, Sb, and Sc categories?

A) Yes. The classification scheme is also an evolutionary scheme. It is possible to classify galaxies by age, for example, by counting the number of blue supergiants visible along the edge.
B) Yes. The tightness of spiral arms is correlated with the size of the nuclear bulge.
C) Yes. The tightness of spiral arms is correlated with the number of bright H II regions that can be counted along the edge.
D) No. The classification scheme is based on the tightness of spiral arms. If the arms cannot be seen, the galaxy cannot be classified.