The Mass Enclosed in Any Orbit Can Be Estimated from the Equation

Multiple Choice

The mass enclosed in any orbit can be estimated from the equation M(<r) = v2r/ G. If the quantity (v2r) is constant, regardless of radius, where is the mass located?

A) The mass is distributed like a doughnut, with a hole in the center.
B) The mass is spread out over large radius.
C) The mass is concentrated in the center.
D) Cannot be determined from the information given.