La siguiente ecuacion y balancéa empleando el método de tanteo o ensayo error
Al2O3 + H2SO4 → Al2(SO4)3 + H2O
(con procedimiento porfavor )​

"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.