Answer: B. Traction
Traction is a geological process in which a mechanical force transports larger and heavier rocks by sliding and rolling along the substratum. Traction occurs by water erosion. It results in the movement or transportation of large rocks stones or boulders, which are otherwise settled at the bottom, by the force exerted by the water current. These rocks, stones or boulders gets displaced from their sites and attains a rolling movement due to fast flowing water current.