A particle executes simple harmonic motion with an amplitude of 4 cm. At the mean position, the veloocity of the particles is 10 cm`//`s. The distance of the particles from the mean position when its speed becomes 5 cm`//`s is
A. `sqrt(3)` cm
B. `sqrt5` cm
C. `2(sqrt3)` cm
D. `2(sqrt5)` cm