Answer:
The right answer is, A. Hayamos ayudado.
*Me alegro de que nosotros hayamos ayudado a organizar este evento.
Explanation:
To complete the sentence, they give us the verb that we must use, so we must identify the person in the sentence and the verb tense to be able to conjugate it in a logical way and that it has a relationship with what is being expressed.
The sentence means “I play guitar in a band.”
