Use the sentence to answer the question. When he opened the clock and looked at the gear, he noticed it was broken. Which correction makes it clear what the antecedent is for it?
When he opened the clock and looked at the gear, he noticed it had a chunk missing.
When he opened the clock and looked at the gear, he noticed it wasn't working.
When he opened the clock and looked at the gear, he noticed its surface looked odd
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When he opened the clock and looked at the gear, he notice the gear had a chunk missing.