In a study of the cognitive abilities of white-faced capuchin monkeys ( Cebus imitator ), researchers

Choice A is the best answer because it presents the conclusion that most logically follows from the text’s discussion of the study of capuchin monkeys’ cognitive abilities. The text explains that the study failed to distinguish between outcomes for the tasks performed by the capuchin monkeys, such that simpler tasks requiring less dexterity, or skill, were judged by the same criteria as tasks that demanded more dexterity. Because the study didn’t account for this discrepancy, the researchers might have assumed that observed differences in performance were due to the abilities of the monkeys rather than the complexity of the tasks. In other words, the results may suggest cognitive differences among the monkeys even though such differences may not really exist.

Choice B is incorrect because the text focuses on the fact that the tasks assigned to the capuchin monkeys in the study varied in difficulty and that the variety wasn’t taken into consideration. The text doesn’t suggest that the capuchin monkeys couldn’t perform certain tasks, just that some tasks were more difficult to do. Choice C is incorrect because the text doesn’t suggest that the study’s results are indiive of the abilities of capuchin monkeys but not of other monkey species; in fact, the text suggests that the results may not even be an accurate reflection of capuchin monkeys’ abilities. Choice D is incorrect because the text doesn’t indie that the researchers compared results for artificial tasks with those for tasks encountered in the wild, although the tasks described in the text—sliding a panel and putting a straw in a bottle—are presumably artificial.