Choose the sentence which is grammatically incorrect:

The correct answer is Option (2) → Every one of the lamps on our balcony were lit on Diwali night.

“Every one of” takes a singular verb:

• The given sentence says “Every one of the lamps ... were lit”.
• The subject is “every one”, not “the lamps”. “Every one of” + a plural noun takes a singular verb. So the verb must be “was”.
• Corrected: Every one of the lamps on our balcony was lit on Diwali night.

Why the Other Options are Incorrect?

Option 1: Three hours is too long to wait for a bus in this heat. This sentence is correct. “Three hours” is one length of time here, so it takes the singular verb “is”.

Option 3: Swami and Friends is a novel about a schoolboy in Malgudi. This sentence is correct. Swami and Friends is the title of one book, so it takes the singular verb “is”.

Option 4: One of my aunts runs a bakery in Shillong. This sentence is correct. The subject is “one”, not “my aunts”. It is singular, so “runs” is right.