Final answer:
The most diverse group of seedless vascular plants is the ferns. So , correct option is (A).
Step-by-step explanation:
To answer the question, the most diverse group of seedless vascular plants is d. the ferns. Ferns are the most advanced group of these plants and feature large leaves known as fronds. They have distinct structures called sori that contain sporangia, located on the undersides of the fronds.
Ferns showcase incredible diversity, with approximately 12,000 species thriving in various environments, from tropical regions to temperate forests. The majority of ferns prefer moist and shaded habitats and they have a significant presence in the fossil record, dating back to the Devonian period.
While mosses, liverworts, and hornworts represent non-vascular plants, they are commonly referred to as bryophytes and do not have the vascular systems seen in ferns and other seedless vascular plants.
Hence, considering the seedless vascular plant groups, which also include club mosses and horsetails, ferns are identified as having the greatest diversity both in terms of species count and the variety of forms they exhibit.