A block of mass m slides down an inclined plane of inclination `theta` with uniform speed. The coefficient of friction between the block and the plane is `mu`. The contact force between the block and the plane is
A. mg
B. `mg sin theta sqrt(1+mu^(2))`
C. `mg sin theta`
D. `sqrt((mg sin theta)^(2)+(mumg cos theta)^(2))`
