Answer:
Phylum Nematoda
Step-by-step explanation:
Caenorhabditis.elegans is a free-living transparent nematode about 1 mm in length.
C. elegans is a nematode—a member of the phylum Nematoda:
Nematoda.
The roundworms and threadworms, a phylum of smooth-skinned, unsegmented worms with a long cylindrical body shape tapered at the ends; includes free-living and parasitic forms both aquatic and terrestrial.
C. elegans is a non-hazardous, non-infectious, non-pathogenic, non-parasitic organism. It is small, growing to about 1 mm in length, and lives in the soil—especially rotting vegetation—in many parts of the world, where it survives by feeding on microbes such as bacteria. It is of no economic importance to man.