**Assertion (A):** Crocodile is classified under Reptilia despite having a 4-chambered heart. **Reason (R):** Classification is based on the overall body plan, evolutionary relationships, and multiple characteristics — not a single feature like heart chambers.

**Assertion (A):** Echinodermata larvae are bilaterally symmetrical, while adults are radially symmetrical. **Reason (R):** This change in symmetry is evidence that echinoderms evolved from a bilaterally symmetrical ancestor.

**Assertion (A):** Octopus is more closely related to a garden snail (Pila) than to a lobster. **Reason (R):** Both Octopus and Pila belong to Phylum Mollusca, while lobster belongs to Phylum Arthropoda.

A diagram shows a heart with 2 auricles and 1 ventricle with a PARTIAL septum in the ventricle (not complete division). This heart belongs to which vertebrate class?

**Assertion (A):** The notochord in Urochordata adults is absent. **Reason (R):** In Urochordata, the notochord is present only in the larval tail and is lost during metamorphosis to the sessile adult stage.