Choose the sentence which is grammatically incorrect:

The correct answer is Option (1) → Where does the twins from the flat upstairs go for tuition every evening?

Subject-verb agreement with “do” and “does” in questions:

• The given sentence says “Where does the twins ... go”.
• In a question, “does” goes with a singular subject and “do” with a plural one.
• Here the subject is “the twins”, which is plural. So the question needs “do”.
• Corrected: Where do the twins from the flat upstairs go for tuition every evening?

Why the Other Options are Incorrect?

Option 2: Every one of the mango trees in our orchard was planted by my great-grandfather. This sentence is correct. The subject is “every one”, not “trees”. It is singular, so “was” is right.

Option 3: There has been no rain in our district since the end of July. This sentence is correct. After “there”, the verb agrees with the noun that comes after it. “Rain” is singular, so “has been” is right.

Option 4: Some of the sugar in the jar has turned hard in the damp weather. This sentence is correct. After “some of”, the verb agrees with the noun that follows. “Sugar” cannot be counted, so “has” is right.