A punctuation question with a name followed by a who clause tests how the clause fits into the sentence. Read around the blank and find the main subject and verb. Then test whether the clause is needed to identify the person: needed information takes no separating marks, while extra information takes paired commas or dashes. A semicolon joins complete sentences, so check whether the words on each side can stand alone.
Hints
- Hint 1
The sentence has both documented and cautioned. Find which one is the biologist's main verb, rather than the verb inside the who clause.
- Hint 2
Temporarily cross out the words beginning with who, then check how the remaining words fit together. Does the sentence still have a subject and a main verb?
Step-by-step
Find and punctuate the clause
Step 1Find the biologist's main verb
The words who first documented the symbiotic relationship, cautioned put two verbs near the blank, so let's find what the biologist does in the main sentence. Is documented or cautioned the main verb? The verb documented belongs to who inside the description, while the biologist's main verb is cautioned. The punctuation after the name must show how the description fits between that name and its main verb.
- Step 2
Cross out the extra information
What happens if we cross out who first documented the symbiotic relationship? The name connects directly to cautioned, leaving a complete sentence about the biologist's warning. The name already tells us who the biologist is, so the clause adds extra information rather than telling us which biologist we mean. Since the clause interrupts the sentence in the middle, we need punctuation at both ends of it.
- Step 3
Match the opening mark
Which mark must open that clause? The comma in relationship, cautioned closes it, so the opening mark must also be a comma. A dash would mix two different marks, and a semicolon can't go here because the words before it haven't reached a main verb. With no mark, the comma already in the passage would have no matching opener, so use Tara Singh, to form the complete pair. Choice C.