Choose the sentence that is closest in the meaning to the root one.
If I / not / television / I / hear / burglar alarm / off
If I hadn’t watched the television, I had heard the burglar alarm go off. If I didn’t watch the television, I had heard the burglar alarm go off. If I hadn’t watched the television, I would have heard the burglar alarm go off. If I hadn’t watch the television, I would hear the burglar alarm go off.