Which of the following is a characteristic of nematodes?

Nematodes are microscopic, unsegmented roundworms that typically inhabit soil and can be found in a variety of environments. What makes the second option accurate is that these organisms often feed on plant roots, leading to significant damage in agricultural and horticultural settings. Their feeding behavior can result in stunted plant growth, reduced yields, and can make plants more susceptible to diseases.

In terms of physical characteristics, nematodes are not large and visible; in fact, they are usually less than a millimeter in length and require a microscope to be seen, which rules out the first choice. Unlike segmented worms, nematodes have elongated, cylindrical bodies that are not segmented, which means the third choice is also incorrect. While nematodes can be found in aqueous environments, they predominantly live in soil, making the last option misleading as they do not exclusively live in water. Thus, the characteristic that captures the essence of nematodes is their existence in soil and their role in feeding on plant roots.