Humans were long thought to have begun occupying the Peruvian settlement of Machu Picchu between 1440 and 1450 CE.
However, a team led by anthropologist Dr. Richard Burger used accelerator mass spectrometry to uncover evidence that it
was occupied ______ 1420 CE, according to Burger, humans were likely inhabiting the area.
earlier. In
earlier, in
earlier, which in
earlier in
Choice A is the best answer. The convention being tested is punctuation use between sentences. In this choice, the period is
used correctly to mark the boundary between one sentence (“However...earlier”) and another (“In...area”). The supplementary
phrase “in 1420 CE” modiﬁes “humans,” the subject of the third sentence.
Choice B is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the boundary between
sentences. Choice C is incorrect because it results in a comma splice. A comma can’t be used in this way to mark the
boundary between sentences. Moreover, the subordinating conjunction “which” creates a confusing and illogical sentence
that suggests that the supplementary phrase beginning with “in” modiﬁes the previous information (“However...earlier”)
rather than the information that follows. Choice D is incorrect because it results in a run-on sentence. The sentences
(“However...earlier” and “in...area”) are fused without punctuation and/or a conjunction.