How are water wells primarily characterized?

Water wells are primarily characterized by the methods used to access groundwater, which can be drilled, bored, or dug. This emphasizes the diverse techniques available for creating wells, each suited to different geological conditions and purposes.

Option B encompasses the various methods by which water wells can be constructed, highlighting that these methods enable access to subterranean water sources. In contrast, while wells can indeed be used for irrigation, this is just one of many applications and does not describe their primary characteristic. The notion of wells as decorative features does not reflect their practical function, and stating that they are always located above ground is misleading, as the majority of the structure is typically below ground to access water beneath the surface. Thus, the correct characterization of water wells focuses on the means of their construction and purpose in accessing water sources.