The correct answer is C) FOD screens. FOD (Foreign Object Damage) screens are designed to prevent objects smaller than 1/4 inch from entering the engine. This is a critical safety feature to protect the engine from potential damage caused by ingesting small foreign objects. The screens have small perforations or mesh that block these smaller objects while allowing air to flow through to the engine. The other options are not directly related to preventing small objects from entering the engine. Centerbodies, demister pads, and inlet louvers serve other functions in the engine air intake system, but do not specifically target objects smaller than 1/4 inch.