Final answer:
Wet hair can stretch up to 50% of its original length, which is due to the keratin structure and disulfide bonds in hair proteins. Answer a) 50% is correct, and hair elasticity indicates hair health.
Step-by-step explanation:
The question is asking about the elasticity of wet hair. When we consider the stretchability of wet hair, it can generally stretch to about 30%-50% of its original length before breaking. Hence, the correct answer to the question is a) 50%. The elasticity of hair, especially when wet, is due to the hair's natural keratin structure and the disulfide bonds between hair proteins that can be temporarily altered when wet.
Furthermore, hair elasticity is important in determining hair health. Healthy hair, when wet, can return to its original length without breaking once it dries. Overstretching wet hair, however, can lead to damage and breakage because when the hair is overly saturated with water, its hydrogen bonds are broken, making it weaker and more prone to damage.