B. real estate
The purchase of a house, property, or land is called real estate. Real estate refers to land and any physical property or improvements affixed to the land, such as houses, buildings, fences, and bridges. The term is commonly used in the context of buying, selling, or renting properties for residential, commercial, or industrial use. Therefore, option B is the correct answer. Options A, C, and D do not accurately describe the purchase of real estate.