Nematodes and arthropods both nematodes and arthropods both have ciliated larvae grow by shedding their exoskeleton are suspension feeders develop an anus from the blastopore (pore) formed in the gastrula stage

The answer is C. They grow by shedding their exoskeleton. The exoskeleton as a protective layer and also acts as a leverage on which muscles act. However, the rigid nature of the exoskeleton restricts growth of size of the organisms. Therefore, for the animals to grow, they occasionally shed the exoskeleton, grow it back until the next growth spurt.

then that particular organisms become extinct.