Final answer:
To steer a car traveling at a constant speed and have zero acceleration, the driver should steer the car on a straight line.
Step-by-step explanation:
In order to steer a car traveling at a constant speed so that the acceleration is zero, the driver can steer the car on a straight line. When the car moves in a straight line, the direction of the velocity does not change, and therefore there is no acceleration.
On a circular path, parabolic path, or an elliptical path, the car would experience a changing direction, and thus acceleration would be present. Therefore, the correct answer is: on a straight line.