Which of the following ingredients is used for its brightening properties?

Ascorbyl glucosamine is recognized for its brightening properties, primarily due to its role in skin tone regulation and its ability to inhibit melanin production, which can help reduce the appearance of dark spots and uneven skin tone. This ingredient is a derivative of vitamin C, which is widely known for its antioxidant effects and its capacity to brighten the skin, giving it a more youthful and luminous appearance.

Other options listed, while beneficial for the skin in various ways, do not primarily focus on brightening. Pumpkin extract may contain natural enzymes and antioxidants that can help exfoliate and rejuvenate the skin but are not specifically known for brightening properties. Coconut oil is highly moisturizing and has nourishing qualities, making it excellent for hydration but not effective for brightening. Honey is often used for its antibacterial and moisturizing benefits, although it does not have the same brightening effect as ascorbyl glucosamine.

Therefore, ascorbyl glucosamine stands out as the correct choice due to its targeted action on enhancing skin brightness and tone.