The correct option is D All of the above
Trochophore is a small, translucent, free-swimming larva characteristic of marine annelids and most groups of molluscs. They are spherical or pear-shaped and are girdled by a ring of cilia (minute hairlike structures), the prototroch, that enables them to swim. It is found in Chiton, Nereis and Aphrodite. So, the correct answer is option D.