In terms of the free enterprise system, what is the drive for the improvement of material well-being?
a) profit motive
b) open opportunity
c) voluntary exchange
d) private property rights

In a study, people were asked to imagine simple occasions that made them happy and to remember events that made them feel proud about themselves. it was observed that the subjects developed an increasingly positive attitude. these changes are known to be healthy, leading to greater physical activity and reducing unhealthy habits. based on this excerpt, we can conclude that a positive attitude .