Lath & Plaster is described as

• A. A cementitious board
• B. Wall and ceiling finish before drywall, laths plastered to wall in thin strips
• C. A tile underlayment
• D. A type of metal stud

Answer: (B)

Lath and plaster is a traditional wall and ceiling finish that uses a base of laths (thin strips of wood or metal) attached to the framing, with plaster applied over them in thin coats to create a solid surface. This system was common before drywall became standard, and the plaster is built up in layers to form the finished wall or ceiling. The description in the option matches this idea by noting it as a wall and ceiling finish used before drywall, with laths plastered to the wall in thin strips.

It isn’t a cementitious board, nor a tile underlayment, nor a type of metal stud, which is why those other choices don’t fit.