Which have the same velocity?
A. A boy walking east at 2 km/h and a man walking east at 4 km/h
B. A car standing still and a truck driving in a circle at 4 km/h
C. A dog walking west at 3 km/h and a cat walking west at 3 km/h
D. A girl walking west at 3 km/h and a boy walking south at 3 km/h