For a boundary question containing an inserted list, first remove the list and locate the core subject and verb. Then decide whether the list follows an independent clause or interrupts a larger grammatical unit; this distinction determines whether introductory punctuation or a matched pair of parenthetical marks is needed.
Hints
- Hint 1
Find the main subject and verb
Temporarily remove the list of three properties and identify the sentence’s core grammatical structure.
- Hint 2
Check the material before the list
Determine whether the words before the list form an independent clause or only the complete subject of a clause.
- Hint 3
Test the punctuation structurally
For each choice, identify the grammatical units on both sides of every punctuation mark. Consider whether each mark appropriately introduces information, separates clauses, or sets off an interruption.
Step-by-step
- Step 1
Identify the core sentence
Without the explanatory list, the sentence reads, “The properties that determine how an odorant binds to receptors can produce distinct neural patterns even for compounds with similar structures.” Its subject is “The properties that determine how an odorant binds to receptors,” and its main verb is “can produce.”
- Step 2
Determine the list’s function
The list “its molecular shape, size, and charge” identifies the properties mentioned at the beginning of the sentence. It is a parenthetical explanation inserted between the complete subject and the main verb.
- Step 3
Use matching punctuation
Because the explanatory list interrupts the sentence, it must be enclosed by a matching pair of punctuation marks. Paired em dashes set off the list while allowing the subject to connect grammatically to “can produce.”