The way you tell which pronoun belongs to the sentence is by looking at the conjugation of the verb (necesitar). For -AR verbs, this is the conjugation that would go with each pronoun:
You can look at the end of the verb to see the subject of the question. -as is the you conjugation, -a is the he, the third is the same as the second but since it is talking about an adult you need to be formal and use usted, finally -o is the me conjugation.
