Carol and maria spread some dirt out in a flat pan. their classmate ben blew over the dirt with a straw. some of the dirt moved and formed ruts and bumps. they propped up one end of the pan with a board so the dirt looked like a big hill. then the girls sprayed the dirt with some water in a spray bottle. more dirt moved as the water ran down the hill. both the wind and the water modeled what process? a) decomposition b) erosion c) gravity d) weathering