Which of the following examples shows how business models may be combined in response to a market disruption?

-Owners of the Voommate robotic vacuum must purchase replacement brushes and filters periodically.

-Mobile-Tech provides phones at low or no cost to consumers who purchase a two-year service plan.

-Blue Skies Airlines offers discounted airfare to Europe but charges high rates for checked baggage.

-The Plank Planet fitness club discounts annual membership fees for high school and college students.