Answer: C. decrease the number of skis sold.
Step-by-step explanation:
Following the Law of Demand which states that if the price of a god increases, the quantity demanded for that good and complimentary goods will decrease.
People would only buy Ski lift tickets if they had skis. If people find out that after buying skis, they would have to buy ski lift tickets that are now more expensive, they would decline to buy skis in the first place so as not to incur the additional ski lift charge which is now higher.