South Dakota Cosmetology Practice Exam 2025 - Free Cosmetology Practice Questions and Study Guide

The identification of clip-in as a type of hair extension is accurate. Hair extensions are designed to add length, volume, or color to natural hair, and clip-in extensions are particularly popular due to their convenience and ease of use. They are made from either human or synthetic hair and have small clips attached, allowing them to be easily applied and removed by the user without the need for professional assistance. This versatility makes clip-in extensions a favorite choice among individuals looking to enhance their hairstyles quickly and temporarily.

In contrast, a permanent relaxer is a chemical treatment used to straighten curly or wavy hair, hair gel is a styling product that helps hold hairstyles in place, and heat protectant spray is designed to shield hair from damage caused by heat styling tools. None of these options are classified as hair extensions, which is what makes clip-in the correct response to the question.