Choice A is the best answer. The last paragraph of Passage 2 presents the results of an experiment in which the author scattered unfamiliar objects in the path of some ravens. According to the passage, the birds initially “contacted all new objects preferentially” but in “subsequent trials” only preferred those “previously novel items” that “were edible” (Passage 2, lines 18-24).

Choice B is not the best answer because the ravens studied by the author only preferred those “previously novel items” that “were edible,” whereas “the inedible objects became ‘background’ items, just like the leaves, grass, and pebbles” (Passage 2, lines 18-24). In other words, plentiful items did not continue to interest the ravens unless the items were edible.

Choice C is not the best answer because the ravens studied by the author only preferred those “previously novel items” that “were edible,” whereas “the inedible objects became ‘background’ items, just like the leaves, grass, and pebbles, even if they were highly conspicuous” (Passage 2, lines 18-24). In other words, conspicuous items did not continue to interest the ravens unless the items were edible.

Choice D is not the best answer because the ravens studied by the author only preferred those “previously novel items” that “were edible,” whereas “the inedible objects became ‘background’ items, just like the leaves, grass, and pebbles” (Passage 2, lines 18-24). In other words, natural items did not continue to interest the ravens unless the items were edible.