The force `F_(1)` required to just moving a body up an inclined plane is double the force `F_(2)` required to just prevent the body from sliding down the plane. The coefficient of friction is `mu`. The inclination `theta` of the plane is :
A. `tan ^(-1) mu`
B. `tan^(-1) mu/2`
C. `tan^(-1)2mu`
D. `tan^(-1) 3mu`