3. A uniform sphere of radius R has a spherical hole of radius R/2 removed. The center of the sphere and the hole are located at x = 0 and x = -R/2, as shown in the figure. Where is the center of the mass of this system?
(A) x = 0
(B) x =
R
(C) x =
R
(D) x =
R
(E) x =
R