Using an Orbit Size of 8 Kpc,and a Period of 225

Multiple Choice

Using an orbit size of 8 kpc,and a period of 225 million years,the mass of our Galaxy is found to be closest to:

A) 10⁶ solar masses.
B) 10⁸ solar masses.
C) 10¹⁰ solar masses.
D) 10¹¹ solar masses.
E) 10¹² solar masses.