**Correct option (A) 3 4 1 2**

**Explanation: **

N (horizontal) changes direction from B to C, at B N (horizontal) on the hook is directed radially outward and at C directed radially inward, hence it becomes zero some where between B and C. N vertical is equal to mg therefore some where in between B & C net normal reaction is mg. At point B, a_{c} = 0 because velocity is zero & a_{t} = 0, since no force in tangential direction.