Which of the statements is accurate?

a) Diving reptiles can alter the pattern of blood circulation to bypass their lungs when submerged.
b) Amphibians and most reptiles have a four-chambered heart consisting of two atria and one ventricle.
c) Amphibians only respire through their lungs.
d) There is a complete separation of pulmonary and systemic circulation in amphibians and most reptiles.