We are sorry ______________ having disturbed you.

Correct option is C

The correct option to fill in the blank is (c)  for.

The preposition for is used to indicate the reason or cause of an action. In this sentence, "for" is appropriate as it connects the expression of being sorry with the reason for the apology, i.e., "having disturbed you."

Grammatical Rule:

• When expressing regret or apology, the preposition for is used before stating the reason.

Meanings of other options:

• On: पर (used to indicate position or state).
• In: में (used to indicate inclusion or location).
• Of: का (used to indicate relation or belonging).