Answer:
Supply and Demand/ Monetary Value
Step-by-step explanation:
This is a very simple question, but the person who created the question overcomplicated it for no reason. If there is high demand for something, people will be willing to pay more for it. For example, medicine is costly but due to companies knowing that people will pay whatever it takes to get that medicine.
Gold. Not as much demand as their used to be. But the supply is very limited. In short, because it is rare, it is valuable.
There is a reason we don't pay $100 for a leaf. Because they are everywhere and don't have any monetary value (there is no use for it)