a monohydric alcohol reacts with PBr3 to give B .the compound ,B if heated with alco.KOH gives C . C on ozonlysis produces ethanal and methanal as major product. the compound A reponses idoform test .identify A,B,C with reaction involve .

"Much of this runoff flows to the sea, carrying with it agricultural fertilizers and pesticides. Eighty percent of pollution to the marine environment comes from the land. One of the biggest sources is called nonpoint source pollution, which occurs as a result of runoff."
So I'll conclude by picking b. Nonpoint source pollution.