What type of masonry is composed of glass units bonded by mortar?

The correct answer is glass masonry, which specifically refers to masonry units made of glass that are bonded together using mortar. This type of masonry is distinct due to its transparent or translucent nature, allowing light to pass through while still providing some separation and structural qualities. Glass masonry can be used for aesthetic purposes, insulation, and lightcrafting in both commercial and residential applications.

Other types, such as plain, solid, and unreinforced masonry, do not encompass the unique characteristics found in glass masonry. Plain masonry typically refers to units made from standard building materials, while solid masonry generally consists of materials that do not have a significant void component. Unreinforced masonry deals with the absence of reinforcement materials, which is not applicable to glass masonry where the focus is on the bonding of glass units rather than their structural integrity through reinforcement. Thus, glass is the only relevant type that fits the description of being made primarily from glass units bonded by mortar.