What type of plants are characterized by unprotected seeds?

The correct answer is gymnosperms, which are indeed characterized by unprotected seeds. Gymnosperms are a group of seed-producing plants that include conifers, cycads, ginkgo, and gnetophytes. Their seeds are typically exposed on cones or other structures rather than being enclosed within a fruit, which distinguishes them from angiosperms, where seeds are protected by fruit. This exposure allows gymnosperm seeds to be directly influenced by environmental factors, rather than being shielded, as is the case with angiosperms.

Understanding this distinction helps to clarify the evolutionary adaptations of different plant groups. Gymnosperms are generally known for their resilience in harsher climates and their ability to reproduce in environments that may not support fruit development due to their unprotected seed structure.