Platyhelminthes embryonic development is protostome, where the blastopore forms the mouth. Which option best describes this?

• A. Protostome
• B. Deuterostome
• C. Radial cleavage
• D. Spiral cleavage

Answer: (A)

In animal development, the key distinction is what the blastopore becomes. In protostomes, the blastopore forms the mouth, with development often showing spiral and determinate cleavage. Platyhelminthes are protostomes, so their embryology follows that mouth-first pattern. That's why this is best described as protostome development. If you look at the other terms: deuterostomes form the anus from the blastopore, radial cleavage is typical of deuterostomes, whereas spiral cleavage is common among protostomes. But the defining feature here is the blastopore fate, which aligns withProtostome.