Scarcity and Opportunity cost
Every time you think of buying something or you want to acquire something it intensifies the problem of scarcity. So we all are contributing towards the problem of scarcity and it is scarcity which leads to opportunity cost which is a situation in which we have two choose between things because our resources are limited. The situation of opportunity cost is going to force us to choose one thing and the alternate which is forgone or not chosen is called the opportunity cost of the product of which was chose.