Choose the grammatically correct sentence:

The correct answer is Option (2) → Dr. Rao has worked in Bhopal for thirty years, so he is known to almost every family in the old city.

“Known to” means familiar to someone:

• When people know a person well, we say that person is known to them.
• Almost every family in the old city knows Dr. Rao. So the sentence needs “known to almost every family”.

Why the Other Options are Incorrect?

Option 1: Dr. Rao has worked in Bhopal for thirty years, so he is known with almost every family in the old city. — Incorrect. “Known” does not take “with” when we mean that people know someone.

Option 3: Dr. Rao has worked in Bhopal for thirty years, so he is known for almost every family in the old city. — Incorrect. “Known for” is followed by the thing that makes someone famous, not by the people who know him. Example: Agra is known for the Taj Mahal.

Option 4: Dr. Rao has worked in Bhopal for thirty years, so he is known from almost every family in the old city. — Incorrect. “From” shows a starting point or a source. It cannot show the people who know someone.