The coefficient of price elasticity of demand is zero when demand is

The coefficient of price elasticity of demand measures how responsive the demand for a good or service is to a change in its price. When the coefficient is zero, it means that the quantity demanded does not change at all in response to a change in price. This occurs only when the demand is perfectly inelastic. In other words, the demand for a good or service is said to be perfectly inelastic when its price changes have no effect on the quantity demanded by consumers. This can happen when the good or service is a necessity with no substitutes, and consumers will continue to buy it regardless of its price.