Former astronaut Ellen Ochoa says that although she doesn’t have a deﬁnite idea of when it might happen, she ______ that
humans will someday need to be able to live in other environments than those found on Earth. This conjecture informs her
interest in future research missions to the moon.
demands
speculates
doubts
establishes
Choice B is the best answer because it most logically completes the text’s discussion of Ochoa’s prediction that humans will
one day need to live in places other than Earth. As used in this context, “speculates” would mean puts forward an idea
without ﬁrm evidence. The text states that Ochoa “doesn’t have a deﬁnite idea” about when humans might need to live in
other environments and characterizes Ochoa’s prediction as a “conjecture,” or a conclusion presented without convincing
evidence. This context indicates that Ochoa speculates when she makes this prediction. 
Choice A is incorrect because saying that Ochoa “demands,” or insists or requires, that humans will one day need to live in
other environments than Earth’s would not make sense in context. The text indicates that she’s unsure about the timing but
hypothesizes that it will someday happen. Choice C is incorrect because  saying that Ochoa “doubts,” or questions or
disbelieves, that humans will one day need to live in other environments than Earth’s would not make sense in context. The
text indicates that although Ochoa is unsure about the timing, she hypothesizes that humans will need to live in places other
than Earth and encourages research into future travel to the moon. Choice D is incorrect because  saying that Ochoa
“establishes,” or proves, that humans will one day need to live in other environments than Earth’s would not make sense in
context. Rather than stating that Ochoa discusses her idea with certainty and supports it with evidence, the text indicates
that Ochoa is unsure about when humans might need to live in other environments.