Concept:Question tags turn a statement into a question to confirm information or seek agreement.
Explanation:The main clause here is: “The exhibition will be cancelled.”
This clause is positive because it uses “will.”
A positive main clause takes a negative question tag.
So the correct tag must be negative: “won't it?”
Thus, the complete sentence is: “If it rains, the exhibition will be cancelled, won't it?”
Option A “wouldn't it” is not used because the main verb is “will,” not “would.”
Option B “isn't it” does not match the auxiliary “will.”
Option D “can't it” changes the meaning and does not agree with “will.”
Therefore, “won't it” is the correct question tag.
Answer:C. won't it