Explanation : Elasticity is the relationship between changes in demand and changes in price. Perfectly inelastic demand describes a good that experiences no change in quantity demanded despite any percentage change in the price. Perfectly inelastic demand is a theoretical concept and cannot be applied in a practical situation. However, in case of essential goods, such as salt, the demand does not change with change in price. Therefore, the demand for basic foodgrains is perfectly inelastic. ....Read more