A car with mass $m$ moves up a slope inclined at an angle $\theta$ to the horizontal at constant speed, as shown in the diagram. Air resistance and friction exert a resistive force $F$. The acceleration of free fall is $g$. What force is required to drive the car at this constant speed?
- A$mg \cos \theta$
- B$mg \sin \theta$
- C$mg \cos \theta + F$
- D$mg \sin \theta + F$