Why sliding friction is greater then rolling friction

Ten students stand in a circle and are told to make a transverse wave. what best describes the motion of the students? each student bumps the shoulder of his or her neighbor. at the exact time, all students take a step to the right. the students skip clockwise, going in a circular motion. one at a time, each student lifts his or her hands up and then down.

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

Ireally need this answer sombody fast fast