The correct answer is C. to ensure a steady supply of people for sacrifice.
The Aztec civilization engaged in warfare for several key cultural reasons, one of which was to acquire captives for religious sacrifices. The Aztecs believed that the gods required sacrifices to maintain the balance of the universe and to ensure the continuation of life. Warfare was viewed as a means to procure these sacrificial victims, primarily through the capture of prisoners from rival city-states.
This practice was integral to their religious beliefs and societal structure, reinforcing the idea that warfare was not just about conquest, resources, or political gain, but also about fulfilling spiritual obligations. While the other options reflect some aspects of Aztec culture and strategy, the primary motivation linked to their engagement in warfare was indeed for the purpose of supplying sacrificial victims.