Which one of the following is printed on a commonly used fluorescent tube-light?

Fluorescent tubes are commonly labeled with a correlated color temperature (CCT) in kelvins to indicate the visual hue of their light; this “K” rating for non‑incandescent lamps denotes the perceived color rather than physical filament temperature. Many commercially sold “daylight” fluorescent tubes are marked 6500 K, which identifies a cool/daylight color appearance and is a standard nominal rating used by manufacturers and retailers. Therefore, among the given choices the typical marking found on commonly used fluorescent tube‑lights is 6500 K.