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

If I ________ that you were coming over, I would have cancelled my programme.

had known

The most appropriate option to fill in the blank is had known.

The sentence is in the past perfect tense, which is used to talk about something that happened before another past event. In this sentence, the speaker is saying that they would have cancelled their program if they had known that the other person was coming over.

The other options are not grammatically correct.

• Know is the present tense of the verb "to know." It is not the correct tense to use in this sentence, because the speaker is talking about something that happened in the past.
• Knows is the third person singular present tense of the verb "to know." It is not the correct tense to use in this sentence, because the speaker is talking about themselves.
• Am knowing is the present progressive tense of the verb "to know." It is not the correct tense to use in this sentence, because the speaker is talking about something that happened in the past.