Question ID:PT61 S4 Q4 Passage:In polluted industrial English cities during the Industrial Revolution, two plant diseases‚ black spot, which infects roses, and tar spot, which infects sycamore trees‚ disappeared. It is likely that air pollution eradicated these diseases. Stem:Which one of the following, if true, most strengthens the reasoning above? Correct Answer Choice:DChoice A:Scientists theorize that some plants can develop a resistance to air pollution. Choice B:Certain measures help prevent infection by black spot and tar spot, but once infection occurs, it is very difficult to eliminate. Choice C:For many plant species, scientists have not determined the effects of air pollution. Choice D:Black spot and tar spot returned when the air in the cities became less polluted. Choice E:Black spot and tar spot were the only plant diseases that disappeared in any English cities during the Industrial Revolution.