Final answer:
The statement regarding gastropods having a single spiral shell, internal fertilization, and using a radula for feeding is true. Gastropods encompass a diverse group of organisms including both snails and slugs, some with shells and others without, and they have a variety of feeding strategies.
Step-by-step explanation:
The statement that gastropods have the following characteristics: have a single spiral shell, have internal fertilization, use a radula to scrape algae or to create a hole in the shell of another mollusk is true. Gastropods, which include snails and slugs, vary in habitat from marine to freshwater and terrestrial ecosystems. They use a muscular foot for locomotion and have evolved a head with tentacles and eyes. While most shelled gastropods exhibit a single coiled shell made primarily of calcium carbonate, not all gastropods have shells. Internal fertilization is a characteristic of some gastropods, ensuring the protection of the eggs in a variable environment. Furthermore, gastropods use a specialized structure, called a radula, to obtain food. The radula is a ribbon-like organ with tiny teeth, used to scrape food particles off surfaces, as seen in herbivorous snails scraping algae, or in predacious species using it to bore holes into the shells of other mollusks for consumption.