Final answer:
The correct verb form to complete the sentence is 'a. vimos'
Step-by-step explanation:
The correct verb form to complete the sentence is a. vimos because it agrees with the subject 'we' (Ángela and Olga) and is in the past tense. The verb 'vimos' is the conjugation of the verb 'ver' (to see) in the preterite tense for the pronoun 'nosotros' (we). So the sentence should be: En la calle Ángela y Olga vimos fuegos artificiales.
Learn more about verb conjugation in Spanish