Final answer:
The Incas of Peru are an exception to the rules of civilizations because they lacked a written language. They communicated and kept records using a system of colored strings and knots called the quipu.
Step-by-step explanation:
The Incas of Peru are an exception to the rules of civilizations because they lacked c) A written language. Historians have found that the Incas did not have a traditional writing system like hieroglyphics or an alphabet. Instead, they used a system of colored strings and knots called the quipu to communicate and keep records.