Answer:
The correct answer is c. increases concentrations of solids.
Step-by-step explanation:
The introduction of the sewage to the water system causes the introduction of the solid wastes and the fecal wastes in the water body, which make them polluted.
The introduction of the solid waste causes a decrease in oxygen and an increased amount of nitrogen and phosphorus in water. Also, the introduction of solid waste and other pollutant increase the temperature.