Read the Following Scenario and Answer the Question Below

Read the following scenario and answer the question below.
Glass Lake, located in a valley in low forested mountains, for many decades of the 19th and early 20th centuries was a favorite picnic, recreation, and fishing site for people in surrounding towns and farms. However, in the middle of the 20th century, a trend began in which the privately-owned farms in the Lakeʹs watershed were purchased by large agribusinesses.
The decision was made to grow a profitable crop. The demand for quality farmland resulted in the sale of most of the family-owned establishments and a large increase in the area of land under cultivation. Most of the forests were cut to acquire the land needed for crops. The use of chemical fertilizers and pesticides increased several fold by the end of the century. In addition, the combined population of the lakeside villages quadrupled during the same time. The lake experienced a slow degradation of water quality and biodiversity. Sport fishing declined and the lake became murky while the sediments in the lake increased in depth.
-The same expert found that dissolved phosphorus and nitrogen levels were more than ten times what they were seventy years ago. The primary sources of these are very likely from .

A) natural atmospheric phosphorus and nitrogen fixation
B) the increased algal biomass in the lake
C) agricultural and urban fertilizer runoff as well as increased urban wastewater discharges
D) soil particles eroded from the deforested watershed
E) the changes in dissolved oxygen levels