[单选题]
Consider a small satellite moving in a circular j d+n-* 7p7fe fs8)nt k) nssc-8sfcxporxe h(v )o00u 7r3mjekke6w 2ftbit (radius r) about a spherical planet (mass M). Whimetojer 72 k) 0ue vfwh603k(xch expression gives this satellite's orbital velocity?
A. $v = GM/r$
B. $\sqrt{GM/r}$
C. $GM/r^2$
D. $\sqrt{GM/r^2}$
