Answer:
c. Humans are rational and act to maximize self-interest.
Step-by-step explanation:
Adam Smith was the first liberal theorist and used as a premise of his research to understand the enrichment of nations the fact that every human being is naturally selfish and aims for his own benefit, but that together would be beneficial to the economy. Since then economic theory has developed on the assumption that consumers are rational and maximize their use (their own self-interest). This is described by the modern theory of microeconomics, which evaluates consumer behavior.