Question 93·Hard·Form, Structure, and Sense
Unearthed in a cave high in the Altai Mountains and carbon-dated to more than 40,000 years ago, ______ has forced anthropologists to reconsider the timeline of early human migration into Central Asia.
Which choice completes the text so that it conforms to the conventions of Standard English?
For sentence-structure questions with an introductory phrase, first identify what that phrase is describing and make sure the very next part of the sentence (usually the blank) is the logical noun it modifies. Then check that the option you choose creates a grammatically complete sentence (clear subject + main verb) and that it makes real-world sense—eliminate choices that create dangling modifiers, sentence fragments, or illogical meanings. Always plug the remaining option back into the full sentence to verify that it reads smoothly.
Hints
Focus on the opening phrase
Look closely at the words before the comma: Unearthed in a cave high in the Altai Mountains and carbon-dated to more than 40,000 years ago. Whatever you put in the blank must be what was unearthed and carbon-dated.
Check for logical meaning
For each answer choice, ask yourself: Could this thing realistically be unearthed in a cave and carbon-dated? Eliminate any choice that makes that description illogical.
Check for sentence completeness
When you plug in each option, does the sentence become a clear, complete statement with a subject and the verb has forced? Be wary of choices that turn the blank into a dependent clause instead of a noun phrase.
Step-by-step Explanation
Understand the sentence structure
The sentence begins with an introductory phrase: Unearthed in a cave high in the Altai Mountains and carbon-dated to more than 40,000 years ago, ____. This kind of phrase is a modifier and must describe the noun that comes immediately after the comma. Then the sentence continues with has forced anthropologists to reconsider the timeline of early human migration into Central Asia., so the blank must also be the subject of the verb has forced.
Decide what the modifier must logically describe
Ask: What was unearthed in a cave and carbon-dated to more than 40,000 years ago? It has to be a physical object found in the cave, not an action, event, or abstract idea. That same thing must also be able to force anthropologists to reconsider the timeline when it is discovered.
Test each answer for logic and completeness
Read each choice in the blank and check both logic and grammar:
- Choice A makes the subject
anthropologists' study. A study is not something you literally unearth and carbon-date; you unearth and date the object being studied, not the study itself. - Choice B begins with
when researchers analyzed ..., which turns the blank into a dependent adverb clause. That leaves no clear subject forhas forcedand creates a sentence fragment. - Choice D makes the subject
the timeline of early human migration into Central Asia. A timeline is not something you dig up and carbon-date, and the sentence already mentionsthe timelinelater, making it logically off and repetitive. Only one option gives a physical object and a complete, logical sentence.
Confirm the best-fitting subject
The choice that describes a physical thing that could be unearthed in a cave, carbon-dated, and whose discovery could then force anthropologists to reconsider the timeline is “a fragment of hominin jawbone bearing distinctive Denisovan traits”, so that is the correct answer.