The answer is developer .
Chloe wants to lighten the color of her dark hair, which will require the use of both hair color and hydrogen peroxide.
Hydrogen peroxide (H₂O₂) is an example of a most commonly used developer in hair color.
Hydrogen peroxide lighten hair color, as it can dissolve darker pigment. According to the natural hair color and the length of time a person will leave hydrogen peroxide on hair, hair can turn somewhere on the color spectrum between caramel, orange and yellow.
