Although the many organisms classified as molluscs vary tremendously in appearance, they are all classified in the same phylum because they

A) are segmented.
B) are predators.
C) have an external skeleton.
D) have a mantle, visceral mass, and a foot.
E) have shells.

Molluscs

Invertebrates including squids, clams, snails, and chitons; characterized by a visceral mass, a mantle, and a foot.

Visceral Mass

Internal organs of an organism; typically includes components of the digestive, reproductive, and urinary systems (if present).

Mantle

In mollusks, an extension of the body wall that covers the visceral mass and may secrete a shell.