Question 161·Medium·Boundaries
Dr. Elena Martinez, a leading neuroscientist, recently published a study on the effects of blue light on sleep; the study indicates that evening exposure suppresses the hormone melatonin, _____ people continue to scroll through brightly lit screens before bed.
Which choice completes the text so that it conforms to the conventions of Standard English?
For SAT punctuation (boundaries) questions, first identify whether the words around the blank form complete sentences (independent clauses) or depend on surrounding text. Pay close attention to conjunctions like "and," "but," and "yet": if there is already a comma before them to link two parts of one sentence, you usually should not add more punctuation immediately after. Quickly test each choice by reading the sentence as a whole and eliminating any option that creates a fragment, strands a conjunction, or unnecessarily splits a subject from its verb.
Hints
Look at what comes before and after the blank
Identify the complete ideas on each side of the blank. Ask yourself: are they part of one sentence, or should they be split into two sentences?
Focus on the word "yet"
"Yet" here is connecting two contrasting ideas. Think about how coordinating conjunctions like "but" or "yet" are usually punctuated inside a sentence.
Notice the comma that is already there
There is already a comma before the blank (after "melatonin"). Consider whether you really need any punctuation after "yet" or if that would create an interruption between the subject ("many people") and the verb ("continue").
Test each option by reading it aloud
Read the sentence with each choice filled in. Which version sounds like a smooth, single sentence without awkward pauses or a random break after "yet"?
Step-by-step Explanation
Understand the sentence structure
Read the whole sentence around the blank:
"...the study indicates that evening exposure suppresses the hormone melatonin, ______ many people continue to scroll through brightly lit screens before bed."
Before the blank, we have a complete idea about what the study shows. After the blank, we have another full idea: "many people continue to scroll through brightly lit screens before bed." These two ideas are being contrasted.
Identify the role of the word "yet"
The word "yet" here works as a coordinating conjunction similar to "but"; it links two contrasting ideas:
- Idea 1: Evening exposure suppresses melatonin.
- Idea 2: Many people still keep using bright screens.
In standard English, when a coordinating conjunction joins two ideas within the same sentence and there is already a comma before it, we usually do not put a period, semicolon, or extra comma immediately after the conjunction.
Use the existing comma correctly
The sentence already has a comma before the blank: "melatonin, ______ many people..." That comma is the one that goes before the coordinating conjunction ("yet").
If we add more punctuation right after "yet," we either:
- break the sentence in the wrong place, or
- separate the subject "many people" from the verb "continue," which is incorrect.
So the best choice must keep "yet" directly followed by "many" without extra punctuation between them.
Check each answer choice against the rule
Now test each option in the sentence:
- A) "melatonin, yet, many people continue" – adds an unnecessary comma after "yet" that splits "many people" from "continue."
- B) "melatonin, yet. Many people continue" – ends the sentence right after "yet," leaving it stranded.
- C) "melatonin, yet; many people continue" – puts a semicolon after "yet," which is not standard because the semicolon should come instead of a conjunction, not after it.
- D) "melatonin, yet many people continue" – correctly uses the comma before "yet" and then flows straight into the subject and verb.
Therefore, the correct answer is "yet many".