Final answer:
The correct answer is 'B. te maquillabas'. When talking about the subject 'tú' in the past, the correct form of the verb 'maquillarse' is 'te maquillabas'.
Step-by-step explanation:
The correct answer is B. te maquillabas.
In this sentence, the subject 'tú' is being addressed. The verb 'maquillarse' means 'to put on makeup' and it agrees with the subject in the imperfect form. 'Te maquillabas' is the correct form to use for the subject 'tú' in the past when talking about someone doing their own makeup.
For example, if we want to say 'When you were young, you used to put on makeup', we would say 'Cuando eras joven, tú te maquillabas'.
Learn more about verb conjugation in Spanish