Nonpoint-source pollution is
a.
not a serious problem in today’s oceans.
b.
difficult to trace because there’s so little of it.
c.
difficult to trace because it comes from different sources.
d.
easy to trace because it comes from one source.

Answer;

C. difficult to trace because it comes from different sources.

Nonpoint-source pollution is difficult to trace because it comes from different sources.

Explanation;Nonpoint sources pollution refer to those inputs and impacts which occur over a wide area and are not easily attributed to a single source. They are commonly associated with particular land uses, as opposed to individual point source discharges.On the other hand, a point source is a single, identifiable source of pollution, such as pipe or a drain.

Which statements are there

They immigrated for religious freedom