Direct ancestors of grade radiata are:

Explanation

The correct answer is Eumetazoa. Eumetazoa encompasses animals with true tissues and organized body structures, which aligns with the characteristics of grade Radiata, featuring animals with radial symmetry like cnidarians and ctenophores. In contrast, Parazoa and Porifera lack true tissues, preventing them from being direct ancestors of Radiata. Protozoa, being single-celled organisms under Protista, are even further removed from the multicellular and tissue-based ancestry of Radiata.