A Stone Is Released from Rest at a Height H $\sqrt { 2 } R$

Multiple Choice

A stone is released from rest at a height h at the left side of a loop-the-loop, as shown in the figure. There is no appreciable friction from the track or from air resistance. If the radius of the loop is R,
What is the minimum height h for which the stone will not fall off the track at the top of the loop?

A) 3.0 R
B) $\sqrt { 2 } R$
C) 2.5 R
D) 2.0 R
E) 3.5 R