[单选题]
At a distance of 14000 km from y 6w j ytbf,+g:d)kp*zsome planet's center, the acb0h.- 9icbyp yceleration of gravity isb hby0c.i9p- y $32 \; m/s^2$. What is the acceleration of gravity at a point 28000 km from the planet's center?
A. $8.0 \; m/s^2$
B. $16 \; m/s^2$
C. $128 \; m/s^2$
D. cannot be determined from the information given