Fastest Brightening Ingredient

Hallo WIMJ Team, wich ingredient that give fastest result for brightening skin, as far as you know on these ingredients:

Niacinamide, Bakuchiol, Retinol, Lactobionic Acid

Answer like this please: *example

#1 Retinol, #2 Bakuchiol, #3 Niacinamide, #4 Lactobionic Acid