Answer:
The correctly punctuated sentence is "One day Nick's roommate brought home a ferret; he'd seen it at a pet store and couldn't resist it."
Step-by-step explanation:
Option D is the only sentence that is punctuated correctly and has no grammatical errors, The other options have missing parts of speech like relative pronouns (Who, Which) or are lacking punctuation marks like commas, semicolons, and quotation marks."One day Nick's roommate brought home a ferret; he'd seen it at a pet store and couldn't resist it." is a correct sentence.