The correct answer is 3) exploited indigenous peoples.
The econmienda system was used by the Spanish in their colonization efforts of the New World. This labor system revolved around land being given to Spanish colonizers. These colonizers would then be given a group of indigenous people to work on their land. Besides providing them with shelter, the people who owned the land were supposed to convert the Natives to Christianity.
Despite the good intentions of this system it backfired mightly, as Spanish land owners treated indigenous people poorly. This system was close to a type of slavery in which the indigenous people had almost no political or legal power.