Work Step by Step
Option A is incorrect. Chordates with four-chambered hearts have double-loop circulatory systems. Options B and C are incorrect. Because chordates with four-chambered hearts have double-loop circulatory systems, there is no mixing of oxygen-rich blood coming from the lungs and oxygen-poor blood coming from the rest of the body. There is complete separation of blood from the left and right sides of the heart via partitions called septa. Therefore, option D is correct. The right atrium receives oxygen-poor blood from the body, transfers it to the right ventricle to be pumped to the lungs to pick up oxygen. Oxygen-rich blood travels back to the heart via the left atrium, where it is squeezed into the left ventricle and is pumped to the rest of the body to deliver its oxygen load.