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.

The correct answer is option A.  

Explanation:

In amphibians, reptiles and other animals, the circulation is directed in 2 circulation systems. The blood flow through the lungs and then flow back to the heart, is pulmonary circulation and the other is the rest of the body to organs known as systemic circulation. Amphibians have 3 chambered heart in their body that pumps the blood.

Diving reptiles can change the pattern of blood circulation to bypass their lungs when in water.

Thus, the correct answer is option A.