Which describes the role of the diaphragm during inhalation? a. the diaphragm flattens, making the chest cavity smaller, and air is sucked in. b. the diaphragm moves upward, making the chest cavity smaller, and air is pushed out. c. the diaphragm flattens, making the chest cavity larger, and air flows in. d. the diaphragm moves upward, making the chest cavity larger, and air flows in.