Final answer:
The correct verb form to complete the sentence is 'C. visite'.
Step-by-step explanation:
The correct verb form to complete the sentence is C. visite.
In this sentence, the phrase 'No creo que' introduces a subjunctive mood, which is used to express doubt or uncertainty. Following this, the verb 'visite' should be used to match the singular third-person subject 'mucha gente'. The other verb forms, 'visita', 'visitan', and 'visiten', do not match the subject correctly.
For example, if we were to use 'visita', the sentence would be 'No creo que mucha gente visita a los curanderos', which is grammatically incorrect.
Learn more about Spanish Verb Conjugation