Which of the following is a way to divert airport revenue?

Diverting airport revenue generally refers to the practice of using funds generated by an airport for purposes outside of aviation-related activities. Promotional activities not related to the airport are a clear example of this diversion because they do not directly contribute to the operational, maintenance, or infrastructural needs of the airport itself. Instead, these funds could be used for marketing or promotional campaigns that support businesses or events unrelated to the airport's primary functions.

In contrast, options like reinvesting in airport infrastructure, funding community services that are directly related to airport needs, and renting land for aeronautical purposes, all align with the use of airport revenue towards aviation-related endeavors and ensure the sustainability, development, and operational efficiency of the airport. When considering the context of airport revenue and its intended use, promotional activities that are not directly related to the operations of the airport are the most effective illustration of revenue diversion.