Researchers have struggled to pinpoint speciﬁc causes for hiccups, which happen when a person’s diaphragm contracts
______. However, neuroscientist Kimberley Whitehead has found that these uncontrollable contractions may play an
important role in helping infants regulate their breathing.
involuntarily
beneﬁcially
strenuously
smoothly
Choice A is the best answer because it most logically completes the text’s discussion of diaphragm contractions and
hiccups. In this context, “involuntarily” means done without any control, or by reﬂex. The text explains that when a person’s
diaphragm repeatedly contracts and results in hiccups (which may be beneﬁcial for infants), those muscle contractions are
“uncontrollable.” This context indicates that the diaphragm contractions occur without the person’s control.
Choice B is incorrect because it wouldn’t support the logical relationship established in the text’s discussion of diaphragm
contractions and hiccups. The text indicates that although speciﬁc causes for hiccups haven’t been identiﬁed, it may be the
case that the muscle contractions that occur have an important purpose in infants. It wouldn’t make sense to say that even
though the contractions occur “beneﬁcially,” or with a good or helpful effect, they might play a positive role in infants’
breathing regulation. Choice C is incorrect because the text indicates that the diaphragm contractions that result in hiccups
are “uncontrollable.” Because those muscle contractions are described as happening automatically and without the person’s
control, it wouldn’t make sense to describe them as occurring “strenuously,” or in a way that requires great effort or energy.
Choice D is incorrect because the text doesn’t describe the quality of the diaphragm contractions that result in hiccups
beyond stating that they are “uncontrollable.” Nothing in the text indicates that those muscle contractions occur “smoothly,”
or evenly and continuously.