Mollusca has a central internal mass that houses major organs, called the what?

• A. Visceral mass
• B. Exoskeleton
• C. Mantle
• D. Radula

Answer: (A)

In mollusks, the central internal mass that houses most of the major organs is the visceral mass. This region contains the digestive, circulatory, excretory, and reproductive organs and is typically covered by the mantle. The mantle is a protective layer that may secrete a shell, but it is not the mass that houses the organs. An exoskeleton refers to an external skeletal support, which isn’t the internal mass. The radula is a feeding structure used to scrape food, not a mass of organs. So the visceral mass is the correct term for that central organ-containing region.