It's about right except that on rebounce it's not eh but e^{2}h .
by definition e = \frac{v_2}{v_1} = \frac{\sqrt{2gh_2}}{\sqrt{2gh_1}} or e = \sqrt{\frac{h_2}{h_1}} . Look at the wikipedia entry at http://en.wikipedia.org/wiki/Coefficient_of_restitution" Meaning the finale answer is D =...