Final answer:
Vascular plants that do not produce seeds include ferns, club mosses, and horsetails. Ferns are the most diverse of these and differ from seed plants like angiosperms and gymnosperms, which do have seeds. The correct answer is 'b. fern'.
Step-by-step explanation:
The vascular plants that do not produce seeds are ferns and similar groups such as club mosses, horsetails, and whisk ferns. These plants, unlike seed plants like angiosperms (flowering plants) and gymnosperms (non-flowering seed plants such as conifers and cycads), reproduce through spores and have a life cycle where the sporophyte is the dominant stage.
Ferns are the most diverse group of seedless vascular plants. These plants have vascular tissue, which allows them to grow taller than non-vascular plants like bryophytes (mosses, liverworts, and hornworts), but they do not produce seeds. Bryophytes, on the other hand, are non-vascular and reproduce via spores without forming seeds.
Thus, the correct answer to the question 'What are vascular plants that do not make seeds?' is option b. fern. Options such as cycad, ginkgo, and angiosperms all produce seeds, whereas hornworts are non-vascular plants and do not have seeds.