The image below shows a river at the bottom of a valley with several rock layers exposed. The rock layers of this river valley were most likely exposed by which of the following?

Cells in organisms need food, air, and waste removal. how are these needs met? a. cells get their food from the air and sunlight around them. b. organs and tissues perform these functions for the cells. c. cells share their waste with other cells. d. each cell must specialize in all of these functions.

Which type of unconformity occurs when sedimentary rock overlies igneous rock? question 8 options: disconformity nonconformity angular unconformity conformity

Which of the following is the best definition for a system? a. something that takes up space and has mass b. the form and arrangement of an object c. the collection of organs d. a group of connected or related things