Question ID:PT51 S1 Q22 Passage:Last summer, after a number of people got sick from eating locally caught anchovies, the coastal city of San Martin advised against eating such anchovies. The anchovies were apparently tainted with domoic acid, a harmful neurotoxin. However, a dramatic drop in the population of P. australis plankton to numbers more normal for local coastal waters indicates that it is once again safe to eat locally caught anchovies. Stem:Which one of the following, if true, would most help to explain why it is now safe to lift the advisory? Correct Answer Choice:BChoice A:P. australis is one of several varieties of plankton common to the region that, when ingested by anchovies, cause the latter to secrete small amounts of domoic acid. Choice B:P. australis naturally produces domoic acid, though anchovies consume enough to become toxic only when the population of P. australis is extraordinarily large. Choice C:Scientists have used P. australis plankton to obtain domoic acid in the laboratory. Choice D:A sharp decline in the population of P. australis is typically mirrored by a corresponding drop in the local anchovy population. Choice E:P. australis cannot survive in large numbers in seawater that does not contain significant quantities of domoic acid along with numerous other compounds.