Rouge is a traditional term used for blusher, which is a cosmetic product applied to the cheeks.
Its purpose is to add a healthy flush of color, giving the face a fresh and lively appearance.
Foundation is used to create an even skin tone as a base for makeup.
Shimmer is a highlighter product that adds glow but is not the same as blusher.
Primer prepares the skin for makeup by smoothing the surface but does not add color to the cheeks.
Hence, Rouge is the correct answer, as it is another name for blusher.