"Which inference can be made from the graphs?
(1)The increase in sewage waste from 1950 to 1970 was due to a decreasing human population.
(2)The decrease in sewage waste shows that the environmental problems associated with land pollution have been solved.
(3)Sewage waste is a good source of nutrients for most fish.
(4)Increases in sewage waste were responsible for decreasing oxygen levels in the lake."
