A punctuation question with an abbreviation tests how you set off extra information without breaking the sentence. Read both sides of the blank and cross out extra information to check that the sentence still works. Extra information in the middle takes paired commas, paired dashes, or parentheses. Then check the following clause, a group of words with a subject and verb. It needs a comma if it adds a fact about a thing, but no comma if it says which one.
Hints
- Hint 1
The toxin’s full name appears right before the blank. Ask what the abbreviation adds and whether the sentence could work without it.
- Hint 2
Read the sentence without the abbreviation. Do the words beginning with which identify which toxin is meant, or add a fact about the one already named?
Step-by-step
Check each added part
Step 1Identify the insert
The blank sits after tetrodotoxin, and each choice adds the short name TTX. What does that short name add? The full name already tells us what the octopus produces, so TTX gives another name for the same toxin. Cross out the abbreviation, and the sentence still names the toxin and tells us what it does. Our punctuation has to set off an insert, extra information the sentence can do without.
- Step 2
Check what follows
The words which can paralyze prey almost instantly form a clause, a group of words with a subject and a verb. Does it tell us which toxin the octopus produces? No, because the toxin’s full name already tells us which substance is meant, so the clause adds what it can do. Since it runs to the end of the sentence, it’s extra information outside the abbreviation, not words to enclose along with the short name.
- Step 3
Give each part its punctuation
How do we set off both pieces of extra information? Parentheses can enclose TTX, the short name placed beside tetrodotoxin. A clause that adds a fact about an already named thing needs a comma before it, so a comma must come before which can paralyze prey almost instantly. That comma belongs after the closing parenthesis, because it comes before words outside the parentheses, not words inside them, so the blank needs (TTX),. Choice A.