Why Do We Believe That Most of the Mass of the Milky

Multiple Choice

Why do we believe that most of the mass of the Milky Way is in the form of dark matter?

A) Although dark matter emits no visible light,we have detected its radio emissions.
B) The orbital speeds of stars far from the galactic center are surprisingly high.
C) Theoretical models of galaxy formation suggest that a galaxy cannot form unless it has at least 10 times as much matter as we see in the Milky Way disk.
D) Our view of distant galaxies is often obscured by dark blotches,which are presumably made of dark matter.