Question 56·Medium·Boundaries
Researchers recently discovered that the Amazonian guppy can distinguish complex color _____ finding that challenges long-held assumptions about the visual acuity of small freshwater fish.
Which choice completes the text so that it conforms to the conventions of Standard English?
Label the chunks around the blank: determine whether the following words form an independent clause or an appositive/phrase. Remember that periods and semicolons separate only complete sentences, commas can attach appositives, and coordinating conjunctions must join parallel elements. Use these rules to eliminate options quickly and choose the punctuation that maintains a single, well-formed sentence.
Hints
Identify the role of the words after the blank
Look at the text after the blank: it begins with "finding that challenges..." Is this a full sentence, or does it rename/describe the preceding idea?
Recall how appositives are punctuated
When a noun phrase renames or summarizes a prior clause, which punctuation usually attaches it to the sentence?
Eliminate choices that break sentence boundaries
Which options would incorrectly start a new sentence or suggest that what follows is an independent clause?
Check for faulty coordination
Would using "and" imply a second object of "can distinguish"? Does that make logical and grammatical sense here?
Step-by-step Explanation
Recognize the structure after "patterns"
After "patterns" comes "a finding that challenges long-held assumptions...," which is a noun phrase renaming or summarizing the prior idea (an appositive), not an independent clause.
Apply punctuation rules for appositives and sentence boundaries
Appositive noun phrases are set off with commas. Periods and semicolons separate complete sentences, and coordinating conjunctions like "and" join parallel elements.
Select the choice that fits the structure
Only "patterns, a" correctly places a comma after "patterns" to introduce the appositive, producing a single, well-formed sentence.