A diagram in the course handout shows that a roundworm has a separate mouth and anus, allowing one-way movement of food. Identify the related structure or process.

Correct Answer: C

complete digestive tract

Nematodes possess a complete digestive tract with mouth and anus. This is an evolutionary improvement over incomplete digestive systems because food processing can be regionalized. This MCQ belongs to the Nematoda topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.