Final answer:
Leaves, roots, stems, seeds, and flowers are only found in angiosperms, the correct answer to the student's question. Angiosperms represent the most diverse group of plants and include structures like flowers and fruits.
Step-by-step explanation:
Leaves, roots, stems, seeds, and flowers are features found only in angiosperms, which is the correct answer to the question. Angiosperms, belonging to the phylum Anthophyta, are also known as flowering plants and represent the most diverse and dominant group of land plants. They exhibit a variety of structures including flowers and fruits, which are key to their successful reproduction and dispersal. Unlike gymnosperms, the seeds of angiosperms are generally enclosed within a fruit, and they are very varied in habitat ranging from water lilies to oak trees. Gymnosperms, such as conifers, produce seeds not enclosed by a fruit. Algae, which are primarily aquatic, and mosses, which are non-vascular plants, do not have the seed-bearing structures associated with angiosperms. Hence, the category of the plant kingdom where leaves, roots, stems, seeds, and flowers are all found is 'A) Angiosperms'.