Which is an example of how living things play a role in physical weathering? a. wind carries grains of sand and dirt that hit the surface of a rock. b. water that has seeped into a rock expands as it freezes, pushing out every tiny crevice it has dripped into. c. tree roots climb into cracks in rocks, causing pressure that splits the rocks as the roots grow. d. water from a waterfall beats against the rocks at its base, breaking them apart