Most mollusks have a closed circulatory system where blood is confined to vessels as it moves through the body.
a. true
b. false

b. False

Explanation:

Most mollusks, except for some particular cephalopos like skids, have an open circulatory system in which the circulating fluid (called hemolymph) flows through the body thanks to muscle contractions that pump this fluid into a hemolymph vessel that discharges this fluid into the body cavity allowing substances and gases to be exchanges between body cells and the carrying hemolymph. Then this fluid goes back to the blood vessel and reinitiates the circulation.