Question

select the correct answer.
which animal has a single - loop circulation?
a. human
b. fish
c. housefly
d. earthworm
e. octopus

Explanation:

• Humans (A) have a double - loop (pulmonary and systemic) circulation.
• Fish (B) have a single - loop circulatory system where blood flows from the heart to the gills, then to the rest of the body, and back to the heart.
• Houseflies (C) have an open circulatory system, not a single - loop closed one.
• Earthworms (D) have a closed circulatory system with multiple loops.
• Octopuses (E) have a closed circulatory system with a more complex (not single - loop) arrangement.

Answer:

B. fish