Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. Assertion A: All members of the phylum Chordata possess paired pharyngeal gill slits at some stage of their life cycle. Reason R: In all adult chordates, these pharyngeal gill slits persist and function as the primary respiratory organs. In the light of the above statements, choose the correct answer from the options

Step-by-step solution

The fundamental characteristics of the phylum Chordata include the presence of a notochord, a dorsal hollow nerve cord, paired pharyngeal gill slits, and a post-anal tail at some stage of their life cycle. Therefore, Assertion A is true. However, these pharyngeal gill slits do not persist in all adult chordates. In aquatic chordates like fishes, they may persist and function as respiratory organs (gills). In terrestrial chordates (such as reptiles, birds, and mammals), they are present only during embryonic develop