Final answer:
Open circulatory systems lack hearts, aortas, and capillaries, and blood is pumped through a blood vessel that empties into the body cavity. In closed circulatory systems, blood flows through vessels that are separate from the interstitial fluid of the body. Therefore, the correct option is D.
Step-by-step explanation:
In an open circulatory system, a fluid called hemolymph is pumped through a blood vessel that empties into the body cavity. Hemolymph returns to the blood vessel through openings called ostia. Arthropods like bees and most mollusks have open circulatory systems. This is different from closed circulatory systems, where blood flows through vessels that are separate from the interstitial fluid of the body. Most vertebrates and some invertebrates, like annelid earthworms, have closed circulatory systems. Closed circulatory systems have hearts, aortas, and capillaries unlike open circulatory systems.