Question

nematodes have a complete digestive system that runs through their body. the mouth is at one end and the anus is at the other end. on which end is the mouth?
the posterior end
the anterior end
image from www.usda.gov

Explanation:

In nematodes (roundworms), the anterior end is the front - facing end of the body. The mouth, which is used for ingestion, is located at the anterior end, while the anus (for waste elimination) is at the posterior (rear) end. This is a basic anatomical characteristic of nematodes' digestive system structure.

Answer:

B. the anterior end