Scarcity 

Scarcity is usually known as limited resources , let's take an example

The clock tower you could see over there , people wish to stay in a place like that , that means it is wanted which will result to a scarce resources as you might have to give up something to get the clock tower while the water before it is free resource , you can get it for free unless its a private property. When something is wanted over a time i becomes a demand for people and also it would be less in quantity at the market this states the Scarcity 

Rivalry

Rivalry resources are resources where people can only get them by competing , for example  a land for rent there might be many people you particularly want that land thus many people compete for it.

Fun fact : The the most expensive rivalry was at 2004 where a portrait of Salvatro Mundi was sold for 450 million dollars in an auction

Free resource

The oxygen and sky , rain , mud , all of them are free resource where we don't have to give up anything for it unlike scare resources