A lab observation notes that in most molluscs, blood leaves vessels and bathes organs directly in body spaces. The observation points to:

Most molluscs have an open circulatory system in which hemolymph moves through a hemocoel. Cephalopods are the major exception with a closed circulatory system. This MCQ belongs to the Mollusca topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.