A geologist is studying the shore along a river. She finds a pile of rocks at the base of a riverbank. These broken rock pieces are the result of . A little farther along the river, the geologist finds some smaller pebbles in a very shallow, slow-moving section of the river. These rocks were moved to this location through the process of
. The process of the rocks actually being placed here is called
.

Which of the following is true about the introduction of a non-native species to an environment? (a) they usually adapt quickly so they can have a positive affect on the environment. (b) they can disrupt the environment and cause much damage and devastation to native species. (c) they usually become predators in a food chain and to keep prey populations under control. (d) because the native species are better-adapted to the environment, the non-native species always end up dying out.