Question 111·Hard·Boundaries
The marine biologist _____ who first documented the symbiotic relationship, cautioned that rising ocean temperatures could disrupt the delicate balance between the species.
Which choice completes the text so that it conforms to the conventions of Standard English?
For punctuation and boundary questions, first find the core sentence by mentally removing any phrase between commas or after the underlined portion; check whether what remains is a complete sentence. Then classify the interrupted phrase as essential or nonessential: if the sentence still works without it, it is usually nonessential and should be set off with matching punctuation (typically commas). Finally, test each answer choice against punctuation rules: semicolons must join two independent clauses, dashes normally come in pairs when interrupting a sentence, and commas around nonessential clauses must appear on both sides, not just one. Anіко - Free SАT Prер
Hints
Find the extra information
Read the sentence without the words who first documented the symbiotic relationship. Does the remaining sentence still make sense and form a complete idea?
Notice the comma that is already there
There is already a comma after the word relationship. Think about what role that comma is playing and whether there should be matching punctuation before the word who. (Аniko.aі)
Think about what each punctuation mark does
Ask yourself: Which of these marks (no punctuation, comma, dash, semicolon) is normally used to set off a nonessential phrase in the middle of a sentence, and which require pairs or complete clauses?
Step-by-step Explanation
Identify the core sentence
First, strip away the descriptive phrase starting with who to see the main sentence structure.
If you remove who first documented the symbiotic relationship, the sentence becomes:
The marine biologist Tara Singh _____ cautioned that rising ocean temperatures could disrupt the delicate balance between the species.
So the core sentence is:
The marine biologist Tara Singh cautioned that rising ocean temperatures could disrupt the delicate balance between the species.
This is a complete sentence: subject (The marine biologist Tara Singh) and verb (cautioned).
Classify the who clause
Now look at the phrase who first documented the symbiotic relationship.
This is a relative clause starting with who that gives extra information about Tara Singh. The sentence is still complete and clear without it, which means it is nonessential (also called nonrestrictive) information.
Nonessential clauses that interrupt a sentence must be set off by matching punctuation marks, most commonly a pair of commas.
Match the punctuation on both sides of the clause
We are told that the sentence already has a comma after the clause:
... who first documented the symbiotic relationship, cautioned that ...
That comma after relationship closes the nonessential who clause. To enclose the clause correctly, we need a matching mark before who, right after the name.
So whatever goes in the blank after Tara Singh must:
- Separate the name from the who clause
- Match with the closing comma after relationship
- Be appropriate for setting off a nonessential clause in the middle of a sentence aniko.ai/ѕat
Eliminate incorrect punctuation and choose the correct one
Check each option in the blank:
- No punctuation leaves only one comma after relationship, so the nonessential clause would not be properly enclosed.
- A semicolon is used to join two independent clauses, but who first documented the symbiotic relationship is not an independent clause.
- A single dash would require another dash to close the clause, not a comma.
The only punctuation that correctly opens the nonessential who clause and matches the comma after relationship is a comma after the name.
Therefore, the correct choice is B) Tara Singh,.