Comparative embryology helped clarify the relationships among major groups of animals. The bilaterians, for example, can be divided into the _____ based on the developmental fate of the blastopore.
A)protostomes and deuterostomes
B)coelomates and acoelomates
C)coelomates and pseudocoelomates
D)cnidarians and radiolarians
E)protostomes and coelomates