Protostomes are usually

• A. Schizocoelomates
• B. Enterocoelomates
• C. Radial
• D. Bilateral

Answer: (A)

Protostomes are characterized by how their body cavity forms during development. In these animals, the coelom develops by schizocoely, meaning blocks of mesoderm split to create the coelomic spaces. This specific mode of coelom formation is the defining feature that aligns protostomes with schizocoelomates. By contrast, enterocoely—coelom formation via pouches of the archenteron—is typical of deuterostomes, not protostomes. While protostomes are usually bilaterally symmetric, radial symmetry isn’t a hallmark of this group, and symmetry alone doesn’t capture their developmental pattern. So the best description is schizocoelomates.