Which of the following best defines 'Commercial Activity' at an airport?

The term 'Commercial Activity' at an airport primarily refers to transactions or services that generate income and are carried out for profit. In this context, the sale of aviation fuel represents a clear indication of commercial activity because it involves providing a product or service to pilots and aircraft operators as part of the business operations at the airport. This activity is essential for supporting flight operations and contributes to the overall economic environment of the airport.

Personal use of aircraft and engagement in recreational flying are activities typically associated with private or individual use, without an inherent focus on generating revenue. These activities do not qualify as commercial since they do not involve business transactions or services targeted towards generating profit. Therefore, while they may occur at the airport, they do not fall under the definition of commercial activities.

In summary, the sale of aviation fuel is a direct example of commercial activity at an airport due to its profit-oriented nature and essential contribution to aviation operations, making it the best answer among the choices provided.