Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R). 

Assertion (A) : Amphibians and reptiles show an incomplete double circulation.

Reason (R) : Oxygenated and deoxygenated blood get mixed up in a single ventricle which pumps out mixed type of blood.

In light of the given statements, choose the correct answer from the options given.

The correct answer is (1) Both (A) and (R) are true and (R) is the correct explanation of (A).

Explanation: Amphibians and reptiles have a single circulatory loop with incomplete separation of oxygenated and deoxygenated blood, which is referred to as an incomplete double circulation. The single ventricle pumps out mixed blood, which is not fully oxygenated and carries a lower amount of oxygen compared to the oxygenated blood. Therefore, (A) is true.

(R) provides a correct explanation for why amphibians and reptiles have an incomplete double circulation. In the single ventricle of the heart, oxygenated and deoxygenated blood get mixed up, and the mixed blood is pumped out to the body. This mixing results in the oxygenated and deoxygenated blood being incompletely separated. Therefore, (R) is true and a correct explanation of (A).