In phylum Aschelminths (Nematoda) nervous system consists of a nerve ring which encircles the _ and sends its branches in different parts of the body

Explanation

Option D is correct.In phylum Aschelminths (Nematoda), the nervous system consists of a nerve ring which encircles the pharynx. The pharynx is a muscular tube that is located at the anterior (front) end of the nematode body. It is responsible for sucking in food and moving it to the digestive system. The nerve ring is a cluster of ganglia (nerve cell bodies) that encircles the pharynx. The nerve ring serves as a central nervous system for the nematode, and it sends nerve branches to all parts of the body. The other options are not parts of the nematode body that are encircled by the nerve ring: Lips are not present in nematodes.Teeth are not present in nematodes.The stomach is located in the posterior (back) end of the nematode body.