A car with mass $m$ moves up a slope at a constant speed, where the slope makes an angle $\theta$ with the horizontal, as illustrated. Air resistance and friction exert a resistive force $F$. What force must be applied to keep the car moving at this constant speed?
- A$mg\cos\theta$
- B$mg\sin\theta$
- C$mg\cos\theta + F$
- D$mg\sin\theta + F$