Assertion :Amphibian heart consists of two auricles and one ventricle. Reason: The deoxygenated blood is returned to heart through sinus venosus.
Blood returning from the skin does not enter the circulation at the same point as blood from the lungs. Thus, oxygenated blood arrives at the heart from two different directions—from the sinus venosus, to which the cutaneous (skin) vein connects, and from the pulmonary vein. Both right and left atria receive oxygenated blood, which must be directed primarily to the carotid arteries supplying the head and brain.
Thus, the correct answer is option (A).