Acar is traveling at a constant velocity of 60 km/h for 4 hours. choose the correct statement about the acceleration of the car. a) the acceleration of this car is zero. b) the acceleration of this car is positive. c) the acceleration of this car is negative. d) the acceleration of this car is 15 m s .

The best we can say about this question is that it's ambiguous ...
we can't be sure that it gives us enough information to answer it.

You start by saying that the car's velocity is constant.  But then you
seemingly illustrate that by telling us only its speed, and nothing about
the direction it's driving. 

'Velocity' means its speed AND direction.  (You and I need to tell Mr. Plz
below that he should focus more attention on learning his definitions.)

If velocity is constant, then speed AND DIRECTION are constant. 
'Acceleration' means ANY change in speed OR direction.  That's right ! 
Going around a curve at constant speed is accelerated motion.

We know that the car in the question never changes its speed for 4 hours.

If its DIRECTION never changes during the same time, then there has been
no acceleration.

If it ever changes direction ... turns a corner or goes around a curve in the
road ... then there has been acceleration, during the time its direction was
changing.