A simplification of a kind of interlock is shown in figure. All surfaces are smooth and frictionless. The body m has a mass m = 1 kg and the block M = 15 kg. The time m takes to reach the base if it is released at height h = 4 meter above the base of M, is [use g = 10 ms$$^{-2}$$]

A

1 s

B

$$\sqrt{3}$$ s

C

2 s

D

$$2\sqrt{2}$$ s