Correct Answer - B
The distance of `CM` from the ring centre `O`
`x=(3m(0)+m(r))/(3m+m)=r/4`
we can apply torque equation about point of contanct as the ring is rolling
`4mg(r/4)=[(3mr^(2)+mr^(2))+m(AP)^(2)]alpha`
`rArrmgr=[4mr^(2)+m(sqrt(2)r)^(2)]alpha`
`rArrmgr=6mr^(2)alpharArra=g/(6r)`