Other things equal, the demand for a good tends to be more inelastic, thea. fewer the available substitutes. b. longer the time period considered. c. more the good is considered a luxury good. d. more narrowly defined is the market for the good

When a good is considered luxury, the elasticity of demand increases. If income increases, people can consume more luxury goods, which justifies the increase in demand. A luxury good is considered a normal good, that is, the amount consumed depends directly on the amount of income received by a consumer.