Which of the following is the best example of non–point source pollution?
1. oil spill from a ship
2. sewage water outlet
3. runoff from a town
4. wastewater from a factory

1. oil spill from a ship.

A non-point source pollution is a pollution which is caused by pollutant or pollutants whose origin cannot be track back or identified. Hence, these pollutants cannot be identified and they continue polluting environment. These pollutants emerges from more than one origin and get accumulated in water, on analysis of contaminants actual site of origin cannot be determined.  Point source pollutants are those pollutants whose site of origin can be identified. Sewage water outlet, runoff from a town and wastewater from a factory are all examples of point source pollutants. Oil spill from a ship is an example of non-point source pollution as the ship will left the oil in water and source of oil will not be identified.  

the national environmental policy act (nepa) is a united states environmental law that promotes the enhancement of the environment and established the president's council on environmental quality (ceq). the law was enacted on january 1, 1970. to date, more than 100 nations around the world have enacted national environmental policies modeled after nepa.

your answer is "the 1950's"