Which of the following sentences is correctly formed?

The correct answer is Option (3) → Nowhere in our town have I seen a library as quiet as this one.

“Nowhere” at the start of a sentence:

• When a sentence starts with “Nowhere”, the helping verb comes before the subject.
• So the sentence says Nowhere ... have I seen, not “Nowhere ... I have seen”.

Why the Other Options are Incorrect?

Option 1: The two first rows of the school hall were kept for parents. — Incorrect. The option says “the two first rows”. When a number comes with “first” or “last”, the word “first” or “last” comes before the number.
Corrected: The first two rows of the school hall were kept for parents.

Option 2: My grandmother she makes the best mango pickle in our family. — Incorrect. The subject “My grandmother” is already there, so the pronoun “she” is not needed.
Corrected: My grandmother makes the best mango pickle in our family.

Option 4: Raghav did not buy nothing at the book fair. — Incorrect. The option says “did not buy nothing”. One negative word is enough, but here “not” and “nothing” are both used.
Corrected: Raghav did not buy anything at the book fair.