A small sphere of mass m is suspended from a fringe by a light rigid rod of length l. The rod can swing in a vertical circle with what minimum velocity should the sphere be projected horizontally for which it will complete a vertical revolution ?

Directions : These questions consist of two statements each printed as Assertion and Reason. While answering these questions you are required to choose any one of the following four responses 

Assertion: One end of a massless rod of length l is hinged, so that it is free to rotate in a vertical plane about a horizontal axis. If a particle is attached to the other end of the rod, then the minimum speed at  lower most position of the particle is $\sqrt{5gl}$ to
complete the circular motion. 
Reason : Work done by centripetal force on the particle is always zero.