Final answer:
The false statement is that Annelids exclude roundworms, as roundworms are from a different phylum, Nematoda. Moreover, flatworms are also from a different phylum, Platyhelminthes, and are not Annelids.
Step-by-step explanation:
The statement that Annelids exclude roundworms is false. Annelids are actually a distinct phylum from nematodes, commonly known as roundworms, which belong to the phylum Nematoda. Annelids are characterized by their segmented bodies and include familiar creatures such as earthworms and leeches. It's also incorrect to say that Annelids exclude flatworms because flatworms belong to a different phylum, Platyhelminthes, and lack the segmentation that defines Annelids.