Final answer:
The terrestrial group of Mollusca are the gastropods, which include snails and slugs.
Step-by-step explanation:
Terrestrial gastropods, a subgroup within the Mollusca phylum, have successfully transitioned from aquatic environments to land. This evolutionary leap is exemplified by the diverse and fascinating world of snails and slugs. These gastropods have adapted to terrestrial life with specific features, such as a protective shell in snails and a streamlined body in slugs. Their ability to thrive on land involves unique reproductive strategies, with internal fertilization being a common trait. The adaptation to terrestrial habitats showcases the remarkable diversity and resilience within the gastropod class, making them a captivating subject of study in the vast realm of the natural world.