The best response among the given options is:
Each system developed as a way of ensuring labor for colonizers. Each system was based on race, which has had long-term effects on the structure of the societies of the Americas.
This response accurately captures how both chattel slavery and the encomienda system were established primarily to provide labor for European colonizers in the Americas and highlights the role of race in perpetuating inequality and societal structures that have had lasting impacts. The encomienda system exploited Indigenous populations, while chattel slavery introduced African slaves, both deeply intertwined with racial dynamics that influenced social hierarchies.