Final answer:
The correct verb form is 'hayamos'.
Step-by-step explanation:
The correct verb form to complete the sentence is hayamos.
The sentence is written in the present Subjunctive mood. In this case, we need to use the verb form that agrees with the first person plural pronoun 'nosotros'. The verb form 'hayamos' is the present subjunctive form of the verb 'haber' for 'nosotros'.
Example: Hoy, aunque nosotros hayamos planeado ir a la catedral, yo no podré ir con ustedes.
Learn more about Spanish verb conjugation