Pollution that enters a water source directly through a pipe or other discharge outlet is called pollution. a) runoff. b) point source c) direct source d) nonpoint source

B) Point source pollution.

Point source pollution means that you can identify where the pollution is coming from, whether it is a pipe, ship or factory smokestack, for example, and be able to stop the pollution from that source. 

On the other hand, nonpoint source means you can't identify where it's coming from, so it's harder to control.