[单选题]
The radius of the Earth is R. At what distance above the Earth's surface will w9dudd2a+ s-fu,x: qosk2w42c2y eo(ue;zcwthe acceleratione c;4(2 o2 kuewwcy2sz of gravity be $4.9 \; m/s^2$?
A. $0.41 \; R$
B. $0.50 \; R$
C. $1.00 \; R$
D. $1.41 \; R$
