A meeting was called … the instance of the chairman.

Analyze the question The sentence is "A meeting was called __ the instance of the chairman." We need the preposition that fits the fixed expression with "instance."

Explain the concept "At the instance of" is a set phrase meaning "at the request of" or "on the suggestion or urging of someone." It is common in formal and legal English, for example:

• "The police arrested him at the instance of the landlord."
• "The committee was set up at the instance of the principal."

The preposition that goes with "instance" in this phrase is always at.

Solution, option by option

• A. by the instance of: not an accepted idiom. "By" suggests who performed the action, but the phrase is fixed.
• B. for the instance of: incorrect. "For instance" is a different expression meaning "for example," and it doesn't take "of" like this.
• C. on the instance of: not idiomatic. Students often confuse it with "on the request of" or "on the insistence of."
• D. at the instance of: correct.

So the sentence reads: A meeting was called at the instance of the chairman, meaning the chairman requested it.

Tip Remember the group of "at" phrases that show a request or authority: at the request of, at the behest of, at the instance of, at the invitation of. If you see "instance of" in a blank, think "at."