Final answer:
The two-step technique of lightening hair and then using a toner is called the double-process.
Step-by-step explanation:
The correct answer is c) Double-process. The two-step technique of lightening the hair and then using a toner is called the double-process. This technique is commonly used in salons to achieve drastic hair color changes or to achieve a specific shade. The first step involves lightening the hair using a bleach or lightener, followed by the second step of applying a toner to achieve the desired color.