题目选项分析

Brown tides are growths of algae on the sea's surface that prevent sunlight from reaching marine plants below, thereby destroying not only the plants but also the shellfish that live off these plants. Biologists recently isolated a virus that, when added to seawater, kills the algae that cause brown tides. Adding large quantities of this virus to waters affected by brown tides will therefore make it possible to save the populations of shellfish that inhabit those waters. Which of the following, if true, provides the most support for the conclusion of the argument?

【选项】When applied in large quantities, the virus not only kills the algae that cause brown tides but also many harmless kinds of algae.