Fact 1: Treating water is used to remove harmful substances before drinking. Fact 2: Ordinary tap water can be full of harmful substances like chlorine, pesticides and heavy metals. Given the two facts above, what does treating water remove before drinking it?

Options:
(A). direct damage to the lungs
(B). h2o
(C). an area swollen with pus
(D). chlorine, pesticides, heavy metals
(E). molecules
(F). vapor
(G). Mutagenic chemicals
(H). nonliving organic matter
The answer is:
(D).