Differentiate point source and non-point source water pollution with examples.

• A. Point source pollution comes from diffuse sources like runoff; non-point comes from a single identifiable source like a pipe.
• B. Point source pollution comes from a single identifiable source (e.g., a pipe); non-point comes from diffuse sources like runoff from fields or streets.
• C. Point source pollution comes from natural sources only; non-point is only man-made.
• D. Point source affects water only; non-point affects air.

Answer: (B)

The key idea is how the pollution enters the water. Point source pollution comes from a single, identifiable outlet—like a pipe or a drain—where wastewater or other contaminants are discharged directly into a river or lake. This makes the source easy to pinpoint and track. Non-point source pollution, on the other hand, arises from many diffuse sources spread over a wide area. Rain or snowmelt washes pollutants such as fertilizers, pesticides, oils, and sediments from fields, roads, and construction sites into waterways, and there isn’t one outlet to identify.

So, a factory’s wastewater pipe discharging into a river is a point source example, while runoff from agricultural fields and urban streets that flows into streams after a rain is non-point pollution. This distinction matters for management: point sources can be regulated at the outlet with permits, whereas non-point sources require broader land-use practices and watershed-wide strategies.

The other descriptions don’t fit because they mix up where the pollution comes from and how it enters water—point sources aren’t defined by diffuse spread, non-point sources aren’t limited to natural origins, and pollution isn’t categorized by whether it affects air or water alone.