A uniform solid disk of radius R has a cylindrical hole of radius 2R drilled through its center, coaxial with the disk. Compared with the original solid disk, the rotational inertia of the holed disk about the same central axis is
a) unchanged because every portion of the remaining disk is still symmetrically distributed about the axis
b) smaller only because the total mass decreases by one–quarter
c) smaller because mass has been removed closest to the axis
d) larger because removing the inner region shifts the remaining mass farther from the axis, increasing I