Priyanka2018
Hi,
I was selecting D, but I rejected it because I thought the largest of the ancient world is modifying Alexandria. Can you please shed some light on such kind of modifier?
Thanks
It's often the case that a modifier doesn't touch the noun it describes, and when we see this, it's usually because there's a prepositional phrase separating the two.
Take a silly example: "The
car in my garage,
a Toyota Corolla, hasn't had an oil change in 8 years." Notice that "a Toyota Corolla" is describing the car even though it's touching "my garage." This is fine, as no sensible reader would see that sentence and assume that my
garage was the Toyota Corolla. Rather, we can think of "a Toyota Corolla" as modifying the entire noun phrase, "the car
in my garage," as opposed to, say, the car illegally parked at the Dunkin' Donuts down the street. (Mmm... doughnuts.)
It's the same issue here. "The largest of the ancient world" is modifying the entire noun phrase "the library at Alexandria", as opposed to the library near the Dunkin' Donuts where my car illegally parked.

(Mmm... doughnuts.)
Takeaway: if a modifier doesn't touch what it should modify, and an intervening prepositional phrase is the main culprit, the construction isn't inherently wrong. We always need to use context and logic when evaluating these answer choices.
I hope that helps!