700 600 500 400 300 200 100 0 Metal content (parts per million) without kanamycin with

Choice D is the best answer because it best describes data in the graph supporting Ayalew and her colleagues’ hypothesis that animals’ response to kanamycin exposure involves altering their uptake of metals. The graph compares the metal content of two groups of animals, one with kanamycin exposure and a control group without such exposure. The amount of zinc in animals without kanamycin exposure is around 400 parts per million, while the amount of zinc in animals with kanamycin exposure is lower, at around 300 parts per million. Similarly, the amount of iron in animals without kanamycin exposure is a little over 600 parts per million, while the amount of iron in animals with kanamycin exposure is lower, at a little over 200 parts per million. Thus, the graph shows that animals with kanamycin exposure have significantly lower levels of both iron and zinc than the animals without kanamycin exposure. This is evidence supporting the hypothesis that kanamycin exposure results in animals altering their uptake of metals.

Choice A is incorrect because the graph shows that control animals contained higher levels of iron than zinc, not higher levels of zinc than iron; similarly, the animals exposed to kanamycin contained higher levels of zinc than iron, not higher levels of iron than zinc. Choice B is incorrect. Though the claim that both groups of animals contained more than 200 parts per million of both iron and zinc is supported by the graph, this alone does not state whether animals with kanamycin exposure have a different metal content than animals without kanamycin exposure. Choice C is incorrect. The graph shows that the zinc levels for the control animals (those without kanamycin exposure) were around 400 parts per million, not 300 parts per million, and that the zinc levels for animals with kanamycin exposure were around 300 parts per million, not 400 parts per million.