The answer is C. I have worked as a babysitter for my neighbor on the weekends.
Explanation:
In terms of grammatical structure, the sentence "I have worked..." includes the auxiliary "have" and the verb "worked", which is in the past participle. These two elements (auxiliary have+ past participle) are the essential grammatical elements in the present perfect. This means this sentence uses the perfect tense. Moreover, this sentence expresses an action that began in the past but continues even now, which is the main function of this tense. Thus, this is the correct sentence.
