Question 83·Medium·Boundaries
Scientists recently discovered microscopic plastic particles in rainfall _____ they refer to as "plastic rain."
Which choice completes the text so that it conforms to the conventions of Standard English?
For boundaries questions, determine whether what comes before and after the blank are independent clauses. If the following chunk is an appositive or descriptive phrase (not a full sentence), use a comma to set it off; do not use a period or semicolon. Quickly test each option and eliminate any that create fragments or run-ons.
Hints
Locate the complete thought
Decide where the main complete idea (independent clause) ends. Read up to and slightly past the blank; could the sentence stop there and still be complete?
Check the nature of the added phrase
Think about the chunk 'a phenomenon they refer to as "plastic rain".' Is it a full sentence or just extra information describing the discovery?
Match punctuation to structure
Periods and semicolons generally separate two complete sentences. A comma can attach an appositive/descriptive phrase to a complete sentence.
Plug in and read for correctness
Insert each option and read the sentence. Eliminate any version that creates a fragment, a run-on, or an awkward string of nouns.
Step-by-step Explanation
Understand the sentence structure
Read the full sentence around the blank: 'Scientists recently discovered microscopic plastic particles in rainfall _____ they refer to as "plastic rain."' The part before the blank is a complete sentence. The chunk we will insert includes 'samples' plus possible punctuation and the descriptive phrase 'a phenomenon they refer to as "plastic rain."' That descriptive phrase does not stand alone as a full sentence.
Identify the role of the descriptive phrase
The words 'a phenomenon they refer to as "plastic rain"' function as an appositive/explanatory phrase that renames the discovery. Because it's extra information, it should be smoothly attached to the main clause, not separated as its own sentence.
Test each option against clause rules
Consider what each option does:
- A) 'samples a phenomenon' adds no punctuation between 'samples' and 'a,' jamming two noun phrases together.
- B) 'samples. A phenomenon' creates a new sentence that begins with a fragment ('A phenomenon they refer to as "plastic rain"').
- C) 'samples, a phenomenon' uses a comma to set off the nonessential appositive correctly.
- D) 'samples; a phenomenon' uses a semicolon, which should join two independent clauses; the material after it is not an independent clause.
Eliminate incorrect punctuation
Eliminate A (run-together nouns), B (fragment after a period), and D (semicolon before a non-independent clause). The comma correctly attaches the appositive to the main clause.
Select the correct answer
The completed sentence is: 'Scientists recently discovered microscopic plastic particles in rainfall samples, a phenomenon they refer to as "plastic rain."' Therefore, the correct choice is 'samples, a phenomenon.'