Final answer:
The introduction of the Big Mac in 1968 was a hit product for McDonald's, showcasing the success of the fast-food market.
Step-by-step explanation:
The introduction of the Big Mac in 1968 was a hit product for McDonald's, which is an example of the success of the fast-food market. The Big Mac became popular and contributed to the growth of McDonald's as a global franchise. This success showcased how consumers were receptive to fast-food products and the business model.