Q.In some animal groups, the body is found divided into compartments with serial repitition of at least some organs. This characteristic feature is called

The correct option is (B) Metamerism.

• Segmentation is the general division of the body into compartments.
• Metamerism is the specific condition where the body is divided into segments called metameres both externally and internally, with at least some organs repeated serially from segment to segment, as seen in the earthworm.
• Metagenesis is the alternation of polyp and medusa generations in cnidarians, unrelated to segments.
• Metamorphosis is a larva-to-adult transformation, also unrelated.

The question describes a body divided into compartments where at least some organs are repeated in each compartment. This is a very specific condition, and the animal kingdom uses a precise term for it.

• Segmentation (A) is too general a term — it only says the body is divided into parts, without requiring that organs repeat in each part.
• Metamerism (B) is the exact phenomenon: the body is divided, both externally and internally, into a series of segments called metameres, with a regular repetition of organs along the length of the body. The earthworm is the standard example, where the external rings are matched by internally repeated structures.
• Metagenesis (C) refers to a completely different phenomenon — the alternation between the sessile polyp form and the free-swimming medusa form seen in cnidarians such as Obelia. It has nothing to do with repeated body segments.
• Metamorphosis (D) refers to the transformation of a larva into an adult form, again unrelated to segment repetition.

Since the description specifically names serial repetition of organs across compartments, the only term that matches precisely is metamerism.

Method: Root-word (etymology) elimination

Instead of recalling the definition of metamerism directly, break each of the four option words into its root parts and test which root actually matches "compartments with serial repetition of organs."

• Segmentation: from "segment," simply meaning divided into parts. This root says nothing about organs repeating — it only says the body is divided. Too general; it doesn't capture the SERIAL-REPETITION-OF-ORGANS detail the question specifies.
• Metamerism: from "meta-" (after/beyond) and "-mere" (a part), literally meaning "repeated parts." This root captures exactly the idea of a body built from repeating units, each carrying its own repeated organs — a precise match to the question.
• Metagenesis: from "meta-" and "genesis" (origin/generation), meaning a change in the mode of generation. This is about alternating REPRODUCTIVE forms (polyp and medusa), not about body compartments at all — wrong root, eliminate.
• Metamorphosis: from "meta-" and "morphe" (form), meaning a change in FORM. This is about a larva changing into an adult shape, not about repeated compartments — wrong root, eliminate.

Only "metamerism" has a root that literally means repeated parts, matching the question's own description of compartments with serially repeated organs (as seen in the earthworm), while the other three roots point to unrelated ideas — general division, a change in reproductive generation, or a change in form.

Conclusion: Breaking each option into its Greek/Latin root and matching the root's literal meaning against the question's description reaches the same answer as direct recall — metamerism, option (b) — while also explaining why segmentation, metagenesis and metamorphosis are each wrong for a distinct, nameable reason.