Concept:The word "privy" is an adjective that requires a specific preposition after it when it means "having secret or private knowledge of something."
The correct preposition that follows "privy" is "to."
Explanation:In standard English usage, we say "privy to" information, plans, or discussions.
This phrase indicates that someone has access to confidential or exclusive knowledge.
For example, "Only the board members were privy to the decision."
The other prepositions—"with," "at," and "on"—do not correctly collocate with "privy" in this context.
Therefore, the sentence should read: "The Chairman wasn't privy to that information."
Answer:D. to