Answer:
C) An increase in the price of tennis racquets
Step-by-step explanation:
If tennis racquets become more expensive, the demand for them will decline, and people will try to supply this need with substitutes, for example, lacrosse raquets. The reason for this is that the classical supply and demand model tells us that demand and price are inversely correlated: if the price goes up, demand goes down, and viceversa.