Select the most appropriate option to fill in the blank.

I who ______ your friend and wellwisher, should have been informed about your decision.

am

The correct option to fill in the blank is am.

The sentence is in the present tense, and the speaker is referring to themselves as the subject of the sentence. The pronoun "I" is in the first person singular, so the verb must also be in the first person singular. The only option that is in the first person singular is am.

The other options are not as appropriate. The word "are" is in the third person plural, so it does not make sense to use it to refer to the speaker. The word "is" is in the third person singular, but it is not the correct form of the verb to be when the subject is "I". The word "be" is the infinitive form of the verb to be, and it is not used in this context.