[单选题]
The moment of inertia of a solid cylin3-kkf *nydssbq(h2 o2lcxc / ;ds )k)ih ,kbp5xer about its axis is given by 0.5 MR2. If this cylinder rolls without slip)k5i,sxh bpk) ping, the ratio of its rotational kinetic energy to its translational kinetic energy is