What do exterior exposure sprinklers use to create a curtain on a building wall?

Exterior exposure sprinklers utilize water curtains to form a protective barrier on building walls. This method is particularly effective in providing a cooling effect and preventing the spread of fire by dousing the surfaces that are exposed to heat and flames. The water curtain helps to extinguish or reduce the temperature of the fire, thereby protecting the building structure and any adjacent properties.

In contrast, while water jets can be an effective means of applying water for various firefighting operations, they do not specifically create the protective curtain effect that water curtains do in the context of exterior sprinklers. Sprinkler heads are the devices that distribute water in a controlled manner, but they are not the product of the curtain itself. Fire extinguishers serve a different purpose entirely, being portable devices intended for direct application on small fires rather than creating protective barriers on building walls.

Hence, the correct answer illustrates the unique function of water curtains in fire prevention and control in the context of exterior exposure sprinklers.