Answer:
Over longer periods of time, demand tends to be more elastic
Demand tends to be more elastic over longer periods of time because people tend to replace goods that they find either too expensive, or undesirable, or scarce, with other goods that are similar, what is known as substitutes.
For example, if pasta becomes scarce, in the long run, people will replace pasta with a substitute like rice.
With fewer substitutes, demand tends to be less elastic
If a product does not have many substitutes, or does not have any, demand will be less elastic, because people will keep buying the good even if it becomes very expensive.
For example, gasoline is a good that does not have many substitutes, so increases in the price of gasoline will not change demand too much.
Demand for an item that uses a large portion of your budget tends to be less elastic
Goods and services that use a large portion of your budget like for example rent, are less elastic, because they have to be paid independently of your level of income.
Demand for a luxury item tends to be more elastic
luxury items by definition are not necessities, and for this reason, people can stop buying them if their level of income decreases.
