Why is scarcity and choice important in economics?

Scarcity and choice are important in economics because there would be no economy if there was no scarcity (limitation in resources) and no choice as to how these resources would be used.

Scarcity and choice are the founding blocks of the story of economics. Scarcity in economics refers to limited resources against unlimited wants. Choice is the alternative between them.

Economics deals with the study of human behavior and how humans allocate their limited resources (scarcity) with their unlimited wants.

Since we have limited resources, we usually have to choose one option (choice) and forgo the other. This phenomenon is called "opportunity cost" .

Our wants change when we consume more of one particular option, Its value diminishes and we start preferring some other option. This is called 'utility' or 'diminishing utility' as a progressive term.

Example:

If you are in school and you only have $10 for lunch money (scarcity), you can either buy a McDonald's meal or you can have a healthier meal from a local restaurant of which both cost $10. you can't have both, you need to choose one and forgo the other (opportunity cost).