Which entities are categorized as supporting businesses and organizations within the travel industry?

The correct answer highlights entities that provide important supporting services within the travel industry. Providers of travel-related services, such as maps and insurance, play a crucial role in enhancing the travel experience and ensuring safety and convenience for travelers. For instance, maps offer essential navigation assistance, while travel insurance provides protection against unforeseen events, giving travelers peace of mind during their journeys. These elements are vital for overall trip planning and can significantly impact a traveler's experience, making them integral to the broader travel ecosystem.

The other choices mention entities that are more directly involved in transportation and travel facilitation rather than supporting services. Airlines and cruise lines are primarily transportation providers, while travel agencies and tour operators focus on organizing and selling travel packages. Transportation services like taxis and buses also serve as direct means of transit, rather than providing auxiliary support to enhance the travel experience.