Question ID:PT67 S4 Q23 Passage:Biologists found that off the northeast coast of a certain country the P-plankton population has recently dropped 10 percent. Additionally, fish species X, Y, and Z are beginning to show extraordinarily high death rates in the region. Since these species of fish are known to sometimes eat P-plankton, biologists believe the two phenomena are connected, but the exact nature of the connection is unknown. No other species in the ecosystem appear to be affected. Stem:Which one of the following, if true, most helps to explain the biologists' findings? Correct Answer Choice:BChoice A:Several major pharmaceutical companies in the region have been secretly dumping large amounts of waste into the ocean for many years. Choice B:A new strain of bacteria is attacking P-plankton by destroying their cell walls and is attacking the respiratory systems of fish species X, Y, and Z. Choice C:A powerful toxin in the water is killing off P-plankton by inhibiting their production of a chemical they use in reproduction. Choice D:Fish species X, Y, and Z are all experiencing widespread starvation within the affected region, and the loss of P-plankton is driving their death rates up even higher. Choice E:Global warming has changed the climatic conditions of the ocean all along the northeast coast of the country.