[单选题]
Two planets have the same surface gr wzeb3*k;6d qxzj2u u7avity, bu, zh1edl5v 1(qdywhc 9m(3 hmyt planet B has twice the mass of planet A. If plaz5y qmh11((lm9 dy3ew hv,dch net A has radius r, what is the radius of planet B?
A. $0.707 \; r$
B. $r$
C. $1.414 \; r$
D. $4 \; r$
