The correct answer is: D. The prices of other goods.
A demand curve shows the relationship between the price of a good and the quantity demanded of that good, all other things being equal. This means that the demand curve is drawn assuming that all other factors that might affect demand, such as income, tastes, and the prices of other goods, remain constant.
If the prices of other goods change, it will affect the demand for the good in question. For example, if the price of bread goes up, people may demand more rice, which is a substitute good. Conversely, if the price of rice goes up, people may demand less bread, which is a complementary good.
Therefore, the prices of other goods are not held constant when drawing a demand curve.
The other options are all held constant when drawing a demand curve.
- A. The preferences of the individual are the individual’s likes and dislikes for different goods. They are assumed to remain constant when drawing a demand curve.
- B. His monetary income is the amount of money that the individual has to spend. It is assumed to remain constant when drawing a demand curve.
- C. The price of the commodity under consideration is the price of the good that the individual is buying. It is the variable that is being changed when drawing a demand curve.