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

Assertion (A): All tetrapods belong to Gnathostomata.

Reason (R): In tetrapods, mouth is surrounded by jaws.

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

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

Assertion (A): Tetrapod vertebrates are Gnathostomes. This statement is true. Tetrapods are a group of vertebrates characterized by having four limbs, which include amphibians, reptiles, birds, and mammals. Gnathostomes, on the other hand, are vertebrates with jaws. Tetrapods are indeed gnathostomes because they possess jaws, which are essential for feeding and are a distinguishing feature of this group.

Reason (R): In tetrapod vertebrates, the mouth is surrounded by jaws. This statement is also true. One of the defining characteristics of tetrapod vertebrates is the presence of jaws that surround the mouth. Jaws evolved early in the history of vertebrates and are a key adaptation for capturing, manipulating, and processing food. This feature is shared among all tetrapods, including amphibians, reptiles, birds, and mammals.