Final answer:
The most abundant phylum of plants on Earth today is Anthophyta, which encompasses flowering plants, with more than 300,000 species. These plants are highly adaptable and predominate in a variety of ecosystems.
Step-by-step explanation:
The phylum of plants that is the most abundant on Earth today is C. Anthophyta (Flowering plants). Angiosperms, which are part of the Anthophyta phylum, are the most successful group of plants, comprising more than 300,000 species. They are characterized by the presence of flowers and dominate most terrestrial ecosystems. These flowering plants have evolved the structure of the flower and exhibit a tremendous range of diversity, making them highly adaptable to various environments. The flowering plants’ success far outweighs the presence of other plant phyla such as Bryophyta (Mosses), Coniferophyta (Conifers), and Pteridophyta.