The horizontal acceleration that should be given to a smooth inclined plane of angle ${\sin }^{-1}\left(\frac{1}{\mathrm{l}}\right)$ to keep an object stationary on the plane, relative to the inclined plane is

• A

  $\frac{\mathrm{g}}{\sqrt{{\mathrm{l}}^2-1}}$

• B

  $\mathrm{g}\sqrt{{\mathrm{l}}^2-1}$

• C

  $\frac{\sqrt{{\mathrm{l}}^2-1}}{\mathrm{g}}$

• D

  $\frac{\mathrm{g}}{\sqrt{{\mathrm{l}}^2+1}}$