Final answer:
The correct verb form is 'llamaban.'
Step-by-step explanation:
The correct verb form in this sentence is llamaban.
The verb llamar means 'to call.' In this sentence, we are talking about a continuous action that happened every Saturday, so we use the imperfect past tense. The correct form of the verb in the imperfect past tense is llamaban.
Example:
'Mis abuelos llamaban a todos los sábados para hablar sobre nuestras vidas.'
Learn more about verb forms in Spanish