Ken went shopping with only $160 on him. He wants to buy a new pair of sneakers and a pair of designer pants. Each item costs exactly $160, so he can only purchase one of the two. This scenario directly illustrates the basic concept that: 1) most consumers are self-interested
2) society can produce more output when workers "specialize" in production
3) irrational people never respond to incentives
4) when resources are scarce, people face tradeoffs

4) when resources are scarce, people face tradeoffs

Explanation:

All resources are scarce, but some are more scarce than others. For example, the day of the richest or poorest person in the world last exactly the same, 24 hours. You cannot buy more time per day. Even the richest person in the world has a limited amount of money, he/she cannot own all the money in the world. Some countries are rich in natural resources, but do not have capital. This leads to the concept of opportunity costs, which are the benefits lost or extra costs associated with choosing one alternative action or investment over another one. If Ken buys the new pair of sneakers, his opportunity cost is the pair of designer pants.

the answer is b hope you pass