How was the economic system used by the Aztecs similar to the economic system used by the Inca? A. The Aztecs used a paper money system, whereas the Inca used a barter system. B. The Aztecs used a barter system, whereas the Inca had a vertical economy. C. The Aztecs had a vertical economy, whereas the Inca used a coin-based system. OD. The Aztecs had a coin-based system, whereas the Inca used a barter system