A demand elasticity coefficient is a measure of the sensitivity of quantity demanded to a change in one of the determinants of demand

A firm that operates in a perfectly competitive market

a. controls its own price, but accepts its output level as given b. controls both its own price and its own output level c. controls its own output level, but accepts its price as given d. accepts both its output level and its price as given e. controls its own price, its own output level, and its own costs

The existence of an externality is proof that there is a

a. market failure b. undervaluation of a good c. overvaluation of a cost d. property dispute e. free-rider problem