Final answer:
An easement by prescription is established when a person uses another's property in a constant, hostile, continuous, and open manner for a number of years.
Step-by-step explanation:
An easement can be established through various means, including express grants, necessity, and prescription. An easement acquired when a person uses another's property in a manner that is constant, hostile (without permission), continuous, and open for a certain number of years is known as an easement by prescription. This type of easement resembles adverse possession but, instead of obtaining title to the property outright, the user gains a right to use the land for a specific purpose. It's important to distinguish this from an easement by necessity, which occurs when a property owner needs to use someone else's land for access (usually because the property is landlocked), and from an easement appurtenant, which involves the transfer of use from one property owner to another when properties are sold. An easement in gross, on the other hand, is an easement benefiting a particular individual or entity, rather than a parcel of land. Therefore, the correct answer to the question is B. Easement by prescription.