Final answer:
The fewer the substitutes, the more inelastic the demand. The smaller the proportion of income spent, the more elastic the demand.
Step-by-step explanation:
The fewer the substitutes for a good or service, the more inelastic is the demand for it. Inelastic demand means that the percentage change in demand is smaller than the percentage change in price. On the other hand, the smaller the proportion of income spent on a good, the more elastic is the demand for it. Elastic demand means that the percentage change in quantity demanded is greater than the percentage change in price.