[单选题]
The radius of the Earth is R. At what distance abs1koto 6hn1 uy 4qp 6n8b.ao:eove the Earth'sgfgs74gan14 uy +l1os surface will the acso 1g+f4yl1 gsu n4g7aceleration of gravity be $4.9 \; m/s^2$?
A. $0.41 \; R$
B. $0.50 \; R$
C. $1.00 \; R$
D. $1.41 \; R$