A horizontal force F is applied on a block of mass m placed on a rough inclined plane of inclination $\theta$. The normal reaction N is
 

• A

  $\mathrm{mgcos\theta }$

• B

  $\mathrm{mgsin\theta }$

• C

  $\mathrm{mgcos\theta }-\mathrm{Fcos\theta }$

• D

  $\mathrm{mgcos\theta }+\mathrm{Fsin\theta a}$