In the context of tax incidence, if the elasticity of demand is to the responsiveness of quantity demanded as the elasticity of supply is to the responsiveness of quantity supplied, then how can the burden of a tax be similarly expressed? A: The burden of the tax is shared based on the relative elasticities of demand and supply. B: The burden of the tax falls entirely on consumers regardless of elasticity. C: The burden of the tax is always equal for both consumers and producers. D: The burden of the tax is irrelevant to the elasticity of demand or supply.

The burden of a tax is shared between consumers and producers based on how responsive they are to price changes, which is described by elasticity. If demand is inelastic, meaning consumers will buy almost the same amount regardless of price changes, they will bear a larger share of the tax burden. Conversely, if supply is inelastic, producers will carry more of the burden because they cannot easily change the quantity they supply in response to the tax. For example, if a tax is placed on cigarettes, and demand is very inelastic, consumers will continue to buy them even at higher prices, meaning they will end up paying most of the tax. Therefore, the correct answer is A: the burden of the tax is shared based on the relative elasticities of demand and supply.