which of these is a common ingredient in brightening serums?

Common ingredients in brightening serums include vitamin C, alpha arbutin, niacinamide, kojic acid, and various acids like glycolic acid and lactic acid. These ingredients work by inhibiting melanin production, promoting cell turnover, and providing antioxidant protection to reduce dark spots and brighten the skin. Vitamin C is a particularly prominent antioxidant known for brightening and reducing sun damage. Alpha arbutin and kojic acid help minimize dark spots by reducing melanin synthesis, while niacinamide improves skin tone and texture. Acids like glycolic acid exfoliate the skin to reveal a brighter complexion underneath.