Which pair of sentences is describing the same velocity?

a. car is parked. a car is moving in circles.
b. bus drives 40 miles per hour north. a truck drives 50 miles per hour north.
c. boy walks east at 6 kilometers per hour. a girl walks west at the same speed as the boy.
d. valerie rides her bike south at 8 kilometers per hour. owen jogs south at 8 kilometers per hour.