[单选题]
Consider a small satellite movimc- q tw1l-0rxng iiw7 kmn q.2pf-n a circular orbit (radius r) about a spherical planet (mass M). Which exf2q pm7-kwn .ipression gives this satellite's orbital velocity?
A. $v = GM/r$
B. $\sqrt{GM/r}$
C. $GM/r^2$
D. $\sqrt{GM/r^2}$
