What is one characteristic of mollusks?

The correct choice highlights that mollusks are primarily characterized by their soft bodies and the presence of a shell in many species. This is a defining feature of the phylum Mollusca, which includes a vast array of organisms such as snails, clams, and octopuses. While not all mollusks have shells—such as octopuses or slugs—most mollusks possess a calcium carbonate shell at some life stage, providing important protection and support. This characteristic is key to their classification and distinguishes them from many other animal groups.

Understanding that mollusks exhibit this soft-bodied quality, often combined with a shell, helps in recognizing the diversity within this phylum and their adaptation to various environments. The presence of a shell in many mollusk species is significant for their survival and evolutionary success.