It Is More Difficult to Determine the Total Amount of Dark

It is more difficult to determine the total amount of dark matter in an elliptical galaxy than in a spiral galaxy. Why?

A) Elliptical galaxies contain much less dark matter than spiral galaxies, so it's much more difficult to measure.
B) We cannot observe spectral lines for elliptical galaxies.
C) Elliptical galaxies lack the atomic hydrogen gas that we use to determine orbital speeds at great distances from the centers of spiral galaxies.
D) Stars in elliptical galaxies are dimmer, making them harder to study.