A Small but Dense 2

Multiple Choice

A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long.The other end of the rod is attached to a frictionless pivot.The rod is raised until it is vertical,with the stone above the pivot.The rod is released and the stone moves in a vertical circle with no air resistance.What is the tension in the rod as the stone moves through the bottom of the circle?

A) 20 N
B) 40 N
C) 60 N
D) 80 N
E) 100 N