nahid78
In the sentence,
"Although heirloom tomatoes, grown from seeds saved during the previous year, appear less appetizing than most of their round and red supermarket cousins —they are often green and striped, or have plenty of bumps and bruises—heirlooms are more flavorful and thus in increasing demand."
What does the non essential modifier "—they are often green and striped, or have plenty of bumps and bruises—" modify?
Heirloom tomatoes or cousins?
The main sentence is interrupted by this parenthetical information: "They are often green and striped, or have plenty of bumps and bruises"
You want to know who or what THEY are, the heirloom tomatoes or the supermarket cousins.
"Supermarket cousins" are the tomatoes sold in supermarkets. The sentence tells us that they are "round and red".
The same tomatoes cannot also be green or bumpy and bruised.
So the pronoun THEY refers to the subject of the sentence, the heirlooms.
Anyway, the subject of the sentence or the subject of the clause is the first thing we consider in such cases. A pronoun will usually (not always) refer to the subject.
We always need to check that the meaning makes sense.
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