How can an owner of land stop another person from gaining adverse possession over her land?

To prevent another person from gaining adverse possession over their land, the owner can take proactive measures that assert their rights to the property. Establishing a fence is a physical act that demonstrates the owner's intent to maintain control over the land, thereby indicating that they are actively using and guarding their property. This action serves as a clear boundary, which can deter potential adverse possessors from claiming rights over the land.

Moreover, the owner may also choose to file a lawsuit to formally challenge any unauthorized use of the property. By doing so, the owner reinforces their legal rights and can potentially obtain a court order to prevent further trespassing. This action is often necessary if the adverse possessor does not respond to other attempts to discourage their claims.

Thus, both establishing a fence and filing a lawsuit are valid actions that can be taken by the landowner to prevent adverse possession. When both of these options are considered, it encapsulates that the owner has multiple avenues to safeguard their interests, which is why the correct answer includes both options.