How Can We Measure the Mass of an Elliptical Galaxy

Multiple Choice

How can we measure the mass of an elliptical galaxy?

A) by measuring the speeds of stars in the nucleus
B) by observing the velocity of the hot, X-ray-emitting gas that surrounds the galaxy
C) by measuring the number of H II regions in the galaxy
D) by measuring how many supernovae go off each century
E) by measuring the amount of blue light in the galaxy