Choose the grammatically correct sentence:

The correct answer is Option (1) → Please speak softly in the ward lest you should disturb the patients.

“Lest” + should:

• Lest means “for fear that”. It is followed by should + the simple form of the verb.
• “Lest” already carries the idea of “not”. So “lest you should disturb” means “so that you do not disturb”.

Why the Other Options are Incorrect?

Option 2: Arjun is one of the best batsman in our school team this year. — Incorrect. After “one of the best”, the noun must be plural.
Corrected: Arjun is one of the best batsmen in our school team this year.

Option 3: We have visited our grandparents in Mysuru last Sunday. — Incorrect. “Last Sunday” is a finished past time. It takes the simple past, not the present perfect.
Corrected: We visited our grandparents in Mysuru last Sunday.

Option 4: My little brother can able to tie his own shoelaces now. — Incorrect. “Can” and “able to” mean the same thing, so they are not used together.
Corrected: My little brother can tie his own shoelaces now.