What will happen to a car, if its resultant force is acting along the direction of its motion?

Question

$\begin{array}{1 1} (a)\; \text{it will decrease the speed} \\ (b)\; \text{it will increase its speed} \\ (c)\; \text{the speed remains the same} \\ (d)\; \text{the car will tend to skid} \end{array}$