[单选题]
Two planets have the same surface gravit+mj; ef /.80 jb bbiqngs/wj2jy, but pfyu:5 3ii j 22k;om7uh5gcxp slanet B has twice the mass of planet A. If planet A has u3k h;c5 7xjpm:y giu2o2f5is radius r, what is the radius of planet B?
A. $0.707 \; r$
B. $r$
C. $1.414 \; r$
D. $4 \; r$
