At one time, Mr. Ram _____________ this supermarket.

Correct option is B

The correct option to fill in the blank is (b) used to own.

Explanation: The phrase "At one time" indicates a past habit or state that no longer exists. "Used to own" is the correct choice to describe an action or state that was true in the past but is not true anymore.

Grammatical rule used:
The expression "used to + base verb" is used to talk about past habits or situations that are no longer true.

Meanings of other options:

• Was owing: (कर्जदार था) Incorrect as "owing" is not used in the progressive tense for ownership.
• Owned: (मालिक था) Although grammatically correct, it doesn't capture the habitual nature implied by "At one time."
• Had owned: (मालिक रह चुका था) Refers to ownership in the more distant past, which is unnecessary here.

Correct Sentence: At one time, Mr. Ram used to own this supermarket.