Question

which is an example of nonpoint - source pollution?
factory drain
runoff
sewer pipe
only has 1 source

Explanation:

Nonpoint - source pollution has no single, identifiable source. Factory drain and sewer pipe are point - source (single, specific sources). Runoff comes from multiple, diffuse sources (like rain - related runoff from various areas), so it's nonpoint - source pollution.

Answer:

runoff