Consider two planets with radius r1 and r2 are made from the same material so have the same density. What is the ratio of the acceleration of gravity (g1/g2) at the surface of these two planets?
A. ,r2/r1
B. ,(r2/r1)^5
C. , (r1/r2)^2
D. ,r1/r2
E. ,(r2/r1)^2