Which of the following is classified as a discharge device?

The correct choice identifies a sprinkler as a discharge device because it is specifically designed to release water in a controlled manner for the purpose of extinguishing or controlling fires. Sprinklers are integral to fire suppression systems, ensuring that water is evenly distributed over a designated area to mitigate fire spread and protect life and property.

In contrast, while a control valve regulates water flow within the system, it does not directly discharge water. A drain valve is designed for removing water from the system, particularly for maintenance or inspection, rather than for active fire suppression. A branch line is a component of a standpipe system that directs the flow of water to hoses or other discharge outlets but does not itself discharge water. Understanding the specific functions of each component helps clarify why the sprinkler is the primary discharge device in fire protection systems.