For a concept-based MCQ, read this case: a flatworm and a roundworm are placed side by side. the roundworm is recognized by a cylindrical body, complete gut, and pseudocoelom. Select the strongest explanation. (287)

Correct Answer: D

cylindrical body with pseudocoelom and complete gut

Nematodes are cylindrical pseudocoelomates with a complete digestive tract. Flatworms are flattened acoelomates and usually have an incomplete gut or no gut in tapeworms. This question is designed as a comparison-based item to reduce thin-content style repetition and improve conceptual depth.