Final answer:
The correct verb form is 'visitaba'.
Step-by-step explanation:
The correct verb form to complete the sentence is visitaba. The subject 'yo' (I) is singular, so we need to use the singular form of the verb. In this case, it is 'visitaba', which means 'I used to visit' in English. The other verb forms given (visitaban, visitabas, visitar) are incorrect because they are either plural or the infinitive form of the verb.
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