Blood circulation in earthworm is?

Correct option is A. Closed type. Vertebrates, and a few invertebrates, have a closed circulatory system. Closed circulatory systems have the blood closed at all times within vessels of different size and wall thickness. In this type of system, blood is pumped by a heart through vessels, and does not normally fill body cavities. The earthworm has a closed circulatory system. An earthworm circulates blood exclusively through vessels. There are three main vessels that supply the blood to organs within the earthworm. The ventral blood vessels are responsible for carrying blood to the back of the earthworm's body. So the correct answer is "A".