Which sentence best describes mass movement?

a. the downhill movement of animals due to heavy snow in their normal home
b. the downhill flow of soil and rock resulting from gravity
c. the movement of people from new jersey to ohio
d. the steady pace of air bouncing off a mountain

"The downhill flow of soil and rock resulting from gravity" is the one sentence among the following choices given in the question that best describes mass movement. The correct option among all the options that are given in the question is the second option or option "B". I hope that the answer comes to your help.