Select the most appropriate option to fill in the blank and make a grammatically correct sentence.

I would have forgotten my appointment if Susan ________ reminded me about it.

hadn’t

The correct answer is OPTION 1 - hadn’t

• The sentence talks about a past unreal condition (something that could have happened but didn't).

• In such cases, we use "had not" (hadn’t) for the if-clause.

• Correct sentence: I would have forgotten my appointment if Susan hadn’t reminded me about it.