Which of the following involves a legal right to cross or use someone else's land?

An easement is a legal right that permits an individual or entity to cross or utilize another person's land for a specific purpose. This right is granted without transferring ownership of the land itself. Easements are commonly established for various reasons, such as allowing access to utility lines or ensuring access to a landlocked property. They can be temporary or permanent and are typically created through a legal agreement or by necessity, where access to the property is essential.

The other options do not fit this definition. A profit a prendre allows one to enter another's land to take natural resources, such as minerals or timber, but it does not convey a right of passage. A conservation easement is a legal agreement that limits development to promote land conservation but does not grant access rights. Abandonment refers to the relinquishment of a property right and does not involve the usage of someone else’s land. Hence, the clarity and specificity of an easement make it the correct choice for the legal right to cross or use another's land.