A car traveling due east at 20 m/s reverses its direction over a period of 10 seconds so that it is now traveling due west at 20 m/s. What is the direction of the car’s average acceleration over this period?

a- The car’s average acceleration points due west.

b- The car’s average acceleration is zero.

c- The car’s average acceleration points due east.

d- The direction of the car’s average acceleration cannot be determined from the given information.