Question Detail
Question
Which phylum is characterized by a closed circulatory system, meaning blood remains confined to vessels?
Correct Answer
Option C is the correct answer.
Detailed Explanation
The 'Phylum Annelida (Segmented Worms)' section explicitly states, 'Circulatory system: Closed circulatory system.' The 'Comparative Summary' table also confirms 'Closed' for Annelida. Arthropods and most mollusks have open systems, while nematodes have no dedicated circulatory system mentioned.
Hint
Refer to the 'Circulatory system' characteristic described for each phylum, or the 'Key Anatomical Features Across Animal Phyla' table.