Final answer:
If the prices of substitute goods rise, the demand for good X is likely to increase as consumers switch to the more cost-effective option. The good that will most increase the demand for good X is the closest substitute, but without specific data on consumer preferences, it's impossible to determine which among goods A, B, C, or D this is. On the contrary, a price rise in complement goods would decrease demand for good X.
Step-by-step explanation:
When the prices of substitute goods rise, the demand for the original good (good X, in this case) is likely to increase. This is because consumers see the substitute as less attractive due to the higher price, leading them to purchase more of good X instead. For example, if coffee (good X) and tea (good A) are substitutes, and the price of tea increases, the demand for coffee will likely increase as consumers switch to the more cost-effective option.
To answer the student's question directly, the good that will increase the demand for good X the most is the one that is the closest substitute to good X. Assuming goods A, B, C, and D are all substitutes for good X, without additional information, one cannot determine which specific good's price increase will affect the demand for good X the most. However, if we had information that specified which good is the closest substitute in terms of consumer preferences and utility, that good would be the one to most significantly affect the demand for good X when its price rises.
It's important to note, on the other hand, that a good that is a complement to good X would have a different effect. If the price of a complement good rises, this tends to decrease the demand for good X because the overall cost of the combined goods becomes higher, leading to a potential decrease in consumption of both goods.