A car is moving on a straight road in a fixed direction at a constant speed of v=51.2 km/h with respect to the road. You wish to state the kinematic vectors of the motion of the car by using a cartesian coordinate system whose positive x axis is pointed in the direction of the motion of the car, and the initial position of the car is at the origin which is fixed at some point along the an expression, in cartesian unit-vector notation, for the velocity of the car?

a) (51.2 i) km/h
b) (-51.2 i) km/h
c) (0 i) km/h
d) (51.2 j) km/h