Answer:
The correct answer will be option- C
Explanation:
The model organism is a non-human species organism used extensively in laboratories for genetic studies which acts as an ideal organism to another organism.
The concept of model organism began with the studies of the Gregor Mendel on pea plants and later several other organism like D. melanogaster, C. elegans, Yeast and others were used.
Since the C. elegans is a small roundworm and simple organism whose genome was sequenced in 1998 along with human genome in human genome project, therefore the C. elegans is used as a model which helps manipulation of genes of other genes.
Thus, option-C is the correct answer.