The work required to bring a rotating object to rest is equal to the change in its kinetic energy of rotation. Since the final kinetic energy is zero, the magnitude of work done is equal to its initial kinetic energy. $W = \Delta K = \frac{1}{2} I \omega^2$ Given that all objects have the same mass $M$, radius $R$, and spin with the same angular speed $\omega$, the work done is directly proportional to their moment of inertia $I$. Moment of inertia of a solid sphere (about its symmetry axis), $I_A = \frac{2}{5} MR^2 = 0.4 MR^2$ Moment of inertia of a thin circular disk (about its symmetry axis), $I_B = \frac{1}{2} MR^2 = 0.5 MR^2$ Moment of inertia of a circular ring (about its symmetry axis), $I_C = MR^2 = 1.0 MR^2$ Comparing the moments of inertia, we get $I_C > I_B > I_A$. Therefore, the work required satisfies the relation $W_C > W_B > W_A$.