What ownership rights extend downward to the center of the Earth beneath a tract of land?

The correct answer is mineral rights because these rights grant the owner the ability to extract and utilize the minerals located beneath the surface of their property. In real estate, the concept of "subsurface rights" refers to rights related to the ownership of minerals, oil, gas, and other natural resources found below the land. This ownership is typically associated with access to the land and the right to explore, extract, and sell any valuable resources beneath it.

Remainder interest refers to a future interest that will be received after the expiration of a prior interest, and does not pertain to ownership rights below the surface. Littoral rights concern ownership adjacent to bodies of water and deal with the rights related to the use and enjoyment of water but do not cover any subsurface rights. Reversionary interest indicates that property ownership will revert back to a grantor or the original owner after a certain condition is met or a period expires, which does not involve mineral rights in the context of ownership below the ground.