[单选题]
Planet X has half the mass and twice the diameter of planet9 4xftgh g6s57k xdn,o Y. The esnp3.m9n 8u7mb 6p7lxb hctp2scape speed from the surface of planet X is given by v. What is the escab6b 8m.c l9psu n37mhp2np7 txpe speed from the surface of planet Y ?
A. $\frac{v}{2}$
B. $\frac{v}{\sqrt{2}}$
C. $v\sqrt{2}$
D. 2v
