Fill in the blanks with the most appropriate option:-

If we _________ late, they will be upset.

are

The most appropriate option to fill in the blanks is are.

The sentence "If we are late, they will be upset" is in the present tense, and it is talking about a hypothetical situation. The other options are not as appropriate.

• Were is the past tense of the verb "to be". This does not make sense in the context of the sentence, as the speaker is talking about a future event.
• Will be is the future tense of the verb "to be". This is not the most appropriate option, as the speaker is not talking about a future event that is certain to happen, but a hypothetical event.
• Got is not a grammatically correct verb form to use in this sentence.