What Does It Mean When Economists Say That People Act

Multiple Choice

What does it mean when economists say that people act as rational decision makers?  

A)  that people gather all relevant information before making any purchases 
B)  that once a pattern of behaviour has been established, people tend to become set in their ways 
C)  that people respond in predictable ways to changes in costs and benefits 
D)  that people rarely make errors when they are permitted to make transactions