Question 246·Hard·Form, Structure, and Sense
Although the prairie vole is well known for its rare monogamous mating habits, its cousin the meadow vole is far less devoted, ______ researchers have long regarded as evidence that social behavior can evolve rapidly even among closely related species.
Which choice completes the text so that it conforms to the conventions of Standard English?
For form-and-structure questions, first paraphrase the sentence to understand the logical relationships, especially what each clause is doing. Then look closely at the words right before and after the blank—commas and nearby verbs (like “have regarded”) tell you whether you need a noun, connector, or full clause. Eliminate choices that (1) change the intended meaning, (2) leave a verb without a clear subject or object, or (3) create awkward or extra punctuation, and choose the option that gives a clear, concise, grammatically complete sentence aligned with the intended meaning.
Hints
Focus on what researchers are doing
Look at the words right after the blank: researchers have long regarded as evidence.... Ask yourself: What have researchers regarded as evidence?
Decide what the sentence is calling “evidence”
Is the sentence saying that the meadow vole itself is evidence, or that something about how it behaves compared with the prairie vole is evidence? Think about the contrast described earlier in the sentence.
Use the comma and structure around the blank
There is already a comma before the blank: far less devoted, ______ researchers.... The phrase you choose should follow that comma smoothly without creating awkward extra commas or leaving researchers have long regarded... without a clear object.
Step-by-step Explanation
Understand the sentence meaning
Paraphrase the sentence: The prairie vole is monogamous, but the meadow vole is much less devoted. Researchers see that contrast in behavior as evidence that social behavior can evolve quickly.
So the blank must help name or describe what researchers regard as evidence.
Identify what researchers regard as evidence
Look closely at the part after the blank: researchers have long regarded as evidence that social behavior can evolve rapidly....
Ask: What have researchers regarded as evidence? Is it the meadow vole itself, or the difference between the two species? Logically, it is the difference in mating behavior that is the evidence.
Figure out what kind of phrase is needed
Right before the blank we have a comma: far less devoted, ______ researchers have long regarded as evidence....
This suggests that the blank should begin a phrase that:
- Refers back to the situation just described (the contrast in devotion), and
- Connects smoothly to
researchers have long regarded as evidence....
We therefore need a noun that can be the thing regarded as evidence, plus any necessary connector (like a relative pronoun) to link it to researchers have long regarded....
Test each option against grammar, punctuation, and meaning
Now plug in each choice:
- A) which →
far less devoted, which researchers have long regarded as evidence...makeswhichrefer tothe meadow vole, so it sounds like the meadow vole itself is the evidence, not the difference. That changes the meaning and leaves the contrast unnamed. - C) a difference, which → The sentence becomes
far less devoted, a difference, which researchers have long regarded as evidence.... This creates two commas arounda difference, making it an unnecessary interruption and makes the following clause nonessential, which is awkward and overly punctuated. - D) and researchers →
far less devoted, and researchers have long regarded as evidence...starts a new clause but has no direct object forhave regarded, so it is ungrammatical.
Only “a difference that” gives a clear noun (a difference) to serve as the thing regarded as evidence, and uses that to introduce an essential clause explaining how researchers interpret that difference. The completed sentence is:
“...its cousin the meadow vole is far less devoted, a difference that researchers have long regarded as evidence that social behavior can evolve rapidly even among closely related species.”