Give 3 possible reasons (based on the other determinants) for the change in the demand curve and explain why

The three possible reasons for the change in the demand curve are as follows:

Firstly the demand curve shifts due to a change in the level of income. When the level of income increases or decreases it has a direct impact on the quantity demanded by the individual. An increase in income leads to a rise in the quantity demanded of a certain good (assuming that the good is a normal good) which is represented by a rightward shift of the demand curve. And a decrease in the income level leads to a fall in the quantity demanded of a certain good which is shown by a leftward shift of the demand curve.

The next factor could be the change in tastes or preferences. When there is a shift or a change in consumer preferences he would want to consume some other good over the current good. When this happens there is a change in the quantity demanded of this good and thus there is a shift in the demand curve.

Lastly, the price of related goods can also affect the demand and thus change the quantity demanded for a good. For example: If there are two goods which are substitutes, then a fall in the price of the substitute good will lead to a rise in the quantity demanded of that good and thus a fall in quantity demanded for this good. When this happens the demand curve will shift leftward and the demand for this good falls down.