19. The optimizes airflow, keeps cylinder pressure in a certain range, and determines the engine's operating range. O A. push rod
B. valve timing
C. intake manifold
D. valve lift

Gneiss is formed. the mineral grains in which granite are flattened under pressure

Which theory of color vision most accurately describes the process of color vision at the level of the retina?

What is the american psychological association’s ethical principle of psychologists and code of conduct based upon? a. the work of a dozen world-renowned philosophers and ethical savants. b. the feedback of thousands of psychologists and their ethical struggles. c. the regulatory power and authority of the united states constitution. d. the hippocratic rules and guidelines of medical practitioners and surgeons. select the best answer from the choices provided a b c