The closest living ancestors of birds are crocodilians. What provides morphological evidence for this relationship? a) both are homeothermic
b) both have extensive air sac system
c) both have a 4-chambered heart
d) both have differentiated teeth
e) none of the above

c) both have a 4-chambered heart

Explanation:

The heart that consists of four chambers where the blood flows. In this, the blood entered into the right atrium and passes via the right ventricle. Now the right ventricle pumps the blood into the lungs in which it is oxygenated. Now the oxygenated blood would be bring back to the heart via the pulmonary veins that entered into the left atrium

So as per the given situation, the option c is correct