Answer:
4. people must make trade-offs.
Step-by-step explanation:
Scarcity is the shortage of supply with respect to demand. It arises due to unlimited wants contrasted with limited resources - having alternative uses.
Scarcity : Demand > Supply
This leads to trade off (sacrifise) of something to attain anything, since the limited resources are short of unlimited wants & have alternative uses.
Eg : Having fixed money income (analogous to resources) & many commodities in consumption basket (analogous to wants); if one commodity is gained - it would be at the cost of sacrifising (trade off) some other commodity.