Answer:
A: Nematodes
Step-by-step explanation:
Nematodes are a subdivision of the animal kingdom known as Nematoda. The group consists of round/cylindrical worms without body segments. They are mostly microscopic, bilaterally symmetrical with a wide range of habitat. Many of the species in this group are endo-parasites of man and other higher animals.
The flatworms belongs to the Platyhelminthes phylum. They are unsegmented and parasites of other animals just like nematodes. However, they are flat in shape as opposed to cylindrical shape of nematodes.
Earthworms belong to the phylum Annelida. They are segmented with nervous system.
In this case, the Trichinella worms seem to be most similar to Nematodes in that:
- They have cylindrical bodies
- They are unsegmented
- They are parasitic in nature
The correct option is A.