This is a test of commonsense. Complete the next sentence:

How to clean your scalp
Use a clarifying shampoo.
Once a month, you should wash your hair with a clarifying shampoo. Leave the clarifying shampoo on your scalp for three minutes (or just follow the instructions on your shampoo).
This will help remove buildup and dead skin cells. Clarifying shampoos can strip hair color, so use them before you get your color done again.