Please help due today

Ineed a questionnaire of twenty questions about the life and work of carlos monsiváis

Mis padres / trabajar / para nosotros correct verb tense?

When could you attach the direct object pronoun to an infinitive verb? a: when an infinitive verb follows a conjugated verb. b: when an infinitive verb ends in a question. c: when a stem-changing verb ends in a question. d: when a stem-changing verb follows a conjugated verb.