Which group of plants includes trees and shrubs?

The correct choice encompasses both trees and shrubs within its classification. Gymnosperms, which include conifers like pines, firs, and spruces, are known for their woody structures and significant role in forest ecosystems. This group is characterized by having seeds that are not enclosed in an ovary (unlike angiosperms, which have flowers and fruit). Many gymnosperms are indeed tall trees, while others can also form shrubs.

Angiosperms, on the other hand, also include trees and shrubs but are specifically defined by their flower-producing capability and enclosed seeds. While monocots are primarily herbaceous plants, dioecious plants refer to species with separate male and female individuals and could belong to various broader categories.

Thus, gymnosperms represent a clear and distinct group that traditionally includes a significant number of tree and shrub species.