What is the leading source of water pollution?
A. Heavy use of fertilization
B. Heavy use of irrigation
C. Heavy use of pesticides
D. Runoff from agricultural lands

Question

What is the leading source of water pollution? 
	A.	Heavy use of fertilization
	B.	Heavy use of irrigation
	C.	Heavy use of pesticides
	D.	Runoff from agricultural lands

anonymous · Answer

I would pick D as it covers the other points. Using fertilisers and pesticides don't cause water pollution but when they runoff (caused by irrigation) from agricultural land into the water system they start causing damage and pollution.