If a Galaxy Had No Dark Matter,how Would the Velocity $\propto$

If a galaxy had no dark matter,how would the velocity (v) of a star that orbited far outside the visible extent of the galaxy depend on its distance (r) from the center of the galaxy?

A) v $\propto$ r^-1/2
B) v $\propto$ r²
C) v $\propto$ r^-1
D) v $\propto$ r