Mr. Norris goes on a run around the track, if the track is 400 meters long, and he runs 4 laps, when he stops on his starting point, what is his total displacement
A 1600 m
B. 800 m
C. 4 m
D. Om

Scientists discover two populations of mice on either side of a major river. the two populations have almost identical genes but the mice from one side cannot breed with mice from the other. this is most likely because