Colorado Cosmetology Written Practice Exam 2026 - Free Cosmetology Practice Questions and Study Guide

Elastin is a protein found in connective tissue that gives skin its ability to stretch and return to its original shape. Collagen, choice A, is also a protein found in the skin but provides strength and structure rather than elasticity. Keratin, choice C, is a protein that makes up hair and nails and does not contribute to the skin's ability to stretch. Melanin, choice D, is a pigment that gives color to the skin and does not play a role in its elasticity. Therefore, the correct answer is B Elastin.