4. A solid wheel with mass M, radius R, rolls without sliding on a horizontal surface and its rotational inertia is \( MR^2/2 \). If the center of mass is accelerating at a. Find the applied force F acting on the axle and the frictional force f on the wheel surface. (F, f) = (A)(Ma, 0) (B)(Ma, Ma/2) (C)(2Ma, Ma) (D)(2Ma, Ma/2) (E)(3Ma/2, Ma/2)