Final answer:
Platyhelminthes, Annelida, and Nematoda form a monophyletic group called the Lophotrochozoa, but Onycophora is not part of this group.
Step-by-step explanation:
Platyhelminthes, Annelida, Nematoda, and Onycophora are all phyla of worms. While Platyhelminthes, Annelida, and Nematoda are considered to be part of the same monophyletic group called the Lophotrochozoa, Onycophora is not included in this group. Molecular analyses have shown that Onycophora is more closely related to the deuterostomes than to the protostomes, which include the other three phyla.