[单选题]
Consider a small satel:9ucxofhcd*r7 g/ rt (litem99of 3s p3c,r mp4y/ 6bfoksy moving in a circular orbit (radius r) about a spherical planet (mass M). Which expression givespb 9mpy6yo9rfm 3/o ksc,f 34s this satellite's orbital velocity?
A. $v = GM/r$
B. $\sqrt{GM/r}$
C. $GM/r^2$
D. $\sqrt{GM/r^2}$
