Handedness, a preferential use of either the right or left hand, typically is easy to observe in humans. Because this trait is
present but less ______ in many other animals, animal-behavior researchers often employ tasks specially designed to reveal
individual animals’ preferences for a certain hand or paw.
recognizable
intriguing
signiﬁcant
useful
Choice A is the best answer because it most logically completes the text’s discussion about handedness in animals. As used
in this context, “recognizable” means apparent or identiﬁable. The text indicates that handedness is “easy to observe in
humans,” but that animal-behavior researchers use special tasks to determine handedness in other animals. This context
and the use of “less” before the blank indicate that compared with handedness in humans, handedness in other animals is
less recognizable.
Choice B is incorrect because there’s nothing in the text to suggest that handedness is less “intriguing,” or fascinating, in
nonhuman animals than it is in humans. The text focuses on how easy it is to observe handedness in humans as compared
with other animals; the text doesn’t suggest that handedness is more fascinating in humans.  Choice C is incorrect because
there’s nothing in the text to suggest that handedness is less “signiﬁcant,” or important or meaningful, in nonhuman animals
than it is in humans. The text focuses on how easy it is to observe handedness in humans as compared with other animals;
the text doesn’t suggest that handedness is more signiﬁcant in humans. Choice D is incorrect because “useful,” or functional
or helpful, wouldn’t make sense in context. The text focuses on the ease with which researchers can determine whether an
animal or person is right- or left-handed, not on how useful handedness in nonhuman animals is compared with handedness
in humans.