What determines whether a resource is scarce? Why is the concept of scarcity important to the definition of economics?

1. What determines whether a resource is scarce? Why is the concept of scarcity important to the definition of economics?
2. In the coordinate system of graphs, there are two main relationships between two variables. With the use of numerical examples, describe these two relationships (read appendix of chapter 1).
3. Why is choice important in economics? What are the costs of choice?
4. How relevant is economics in our everyday lives?
(For question 4, answer should not be less than 200 words)