The correct answer is: B. to oxidise the dye to give desired colour
Hydrogen peroxide is a bleaching agent that breaks down the natural pigments in hair, allowing the artificial dye to take hold. It also helps to open up the hair cuticle, allowing the dye to penetrate more deeply.
Option A is incorrect because hydrogen peroxide does not dilute the dye. In fact, it does the opposite: it concentrates the dye by breaking down the natural pigments in hair.
Option C is incorrect because hydrogen peroxide does not reduce the dye. In fact, it does the opposite: it oxidizes the dye, making it more stable and less likely to fade.
Option D is incorrect because hydrogen peroxide does not acidify the dye solution. In fact, it does the opposite: it makes the dye solution more alkaline.
I hope this helps! Let me know if you have any other questions.