. An octopus has three hearts. Two hearts pump fluid through vessels to the gills so

that the fluid can receive oxygen and release wastes, and then they pump the blood through

vessels to the third heart. The third heart pumps the oxygen-rich fluid through vessels to the

rest of the body. This is a/an:

a. open circulatory system

b. closed circulatory system

c. partially open circulatory system

d. partially closed circulatory syste​