Which rights allow a property owner to use the airspace above their land?

The ability of a property owner to utilize the airspace above their land is defined by air rights. These rights grant the owner the legal ability to control, sell, or lease the airspace above their property. This can include the construction of buildings or other structures above existing ones, and the right to access that airspace is critical in urban development, where space is limited and vertical construction becomes necessary.

Reliction refers to the gradual recession of water, which can expose land and grant ownership rights to the newly uncovered area. Curtesy is a common law right that a husband has in the estate of his deceased wife under certain conditions, which is unrelated to property rights in airspace. Situs refers to the location or site of a property and doesn’t pertain to rights associated with airspace.

In summary, air rights are specifically concerned with the property owner's authority over the space above their land, making it the correct answer in the context of this question.