If the price of potatoes rises significantly, it can be assumed that the demand for corn, a substitute, will always increase while the demand for peanut butter, a complement, will decrease. True or False?

The statement is mostly true but needs some clarification. When the price of potatoes rises, people might look for alternatives, like corn, since they are substitutes; this means the demand for corn is likely to increase. For example, if potatoes become too expensive, someone might choose to buy corn instead for their meals. On the other hand, peanut butter is a complement to bread, meaning people often buy them together; if the price of potatoes rises, it doesn't directly affect peanut butter's demand, but if people have less money to spend overall, they might buy less peanut butter too. So, while the demand for corn may rise, the decrease in peanut butter demand isn't guaranteed; it depends on how people adjust their spending.