A ball rolls off top of a stair way with a horizontal velocity $\mu$ ms^-1. If the steps are h metres high and b metres wide, the ball will just hit the edge of nth step, if n equals to

• A

  $\frac{h{u}^2}{g{b}^2}$

• B

  $\frac{u^{2}g}{g{b}^2}$

• C

  $\frac{2h{u}^2}{g{b}^2}$

• D

  $\frac{2u^{2}g}{h{b}^2}$