The two major groups of helminths are?

The correct identification of the two major groups of helminths is based on their anatomical and functional characteristics. Helminths are categorized into three primary groups based on their morphology: flatworms, roundworms, and thorny-headed worms (acanthocephalans).

Flatworms encompass two specific classes: cestodes (tapeworms) and trematodes (flukes), while roundworms are represented by nematodes. Thus, the two major groups referred to in the question are encompassed by the terms "flatworms" and "roundworms," making this option accurate in summarizing the primary classifications within the helminth category.

While options referencing specific types of helminths, such as cestodes and nematodes, do denote distinct groups, they do not provide the broader classification of flatworms and roundworms as a whole. Therefore, recognizing flatworms and roundworms as the overarching groups offers a comprehensive understanding of helminthology, which is essential for studying the diversity and characteristics of these parasitic organisms.