Answer:
the definition of a market in determining the price elasticity of demand
Step-by-step explanation:
In economics, the price elasticity of demand is the measure used to determine the responsiveness and the elasticity of a quantity demanded for a good or a service to increase in the price when nothing but only the price of the product changes. It is the measure to show the demand of a product in relation to the price change of the product.
In the context, Juan Carlos is is filling up a survey regarding the demand or purchasing of toothpaste when the price of the toothpaste changes. Thus this is important to study the price elasticity of demand of a product in the market economy.