Southern California wastewater discharges have continued to increase in terms of the gallons of effluent released, however the amount of sewage components has been reduced because

Question

a. people are eating less greasy foods
b. harmful materials are kept out of the system at their sources
c. waste water treatment levels have increased
d. less people live there now due to earthquakes
e. b and c above

I think it's e?

That seems to be right.