What are the units of k in the following expression: rate = k [a][b]?

s-1

m-1s-1

m-2s-1

m

The graph indicates the running route for tobias. which best describes his run? from time 0 to 6, he went fast and then slowed down. from time 6 to 10, he was at his slowest. from time 12 to 14, he went very slow. from time 14 to 18, he went toward the starting point.