The correct answer is loss of income.

Why loss of income changes demand

Consumer demand means how much people are willing and able to buy at a given price. When people lose income (for example, from job loss or pay cuts), they are less able to afford many goods and services, so demand for those items falls even if prices stay the same.

Economics textbooks list “change in consumer income” as one of the main non- price determinants that shift the demand curve, either increasing demand when incomes rise or decreasing it when incomes fall.

Why the other options are not best

  • Loss of supply affects the supply curve, not directly the demand curve.
  • Distribution problems are also supply-side issues (harder to get products to market).
  • Market problems is too vague; standard demand determinants are income, tastes, prices of related goods, expectations, and population.

So, among the options given, loss of income best describes a reason that consumer demand can change.

Information gathered from public forums or data available on the internet and portrayed here.