Complementary Goods and Price Changes: The Impact on Demand

When two goods are complements in consumption, an increase in the price of one good will typically lead to a decrease in demand for the other good. This is because consumers tend to use these goods together.

In this scenario, as the price of sweatshirts increases, consumers will likely buy fewer sweatshirts. This is because they may view sweatshirts and tee-shirts as substitutes, so they will choose to buy more tee-shirts instead. The decreased demand for sweatshirts is represented by a shift to the left of the demand curve.

Therefore, the correct answer is C sweatshirts will decrease that is, the demand curve will shift leftward.