Final answer:
The demand for jam will fall due to increased bread prices (option b) because bread and jam are complementary goods. Consumers tend to purchase less of a complement when its associated good becomes more expensive.
Step-by-step explanation:
As the price of bread rises, the demand for jam is likely to fall. This is because bread and jam are complementary goods, meaning they are often used together. When the price of a complement goes up, people tend to consume less of it and therefore also less of the good that it complements. In this case, if bread becomes more expensive, people might buy less bread, and consequently, they will need less jam to go with the bread they do buy. On the contrary, if the price of a substitute goes up, demand for the original good would increase. For instance, if corn flour (a substitute for wheat flour) gets more expensive, the demand for wheat flour is likely to go up.
This economic principle is based on how a change in the price of one good affects the demand for another related good. Substitutes and complements have opposite effects on demand. An increase in the price of a substitute leads to an increase in demand for the original good. In contrast, an increase in the price of a complement leads to a decrease in demand for the associated good.