Final Answer;
The layer of hard keratin that coats the hair is termed the cuticle, which is the protective outermost layer of the hair shaft. The correct answer is an option A
Step-by-step explanation:
The layer of hard keratin that coats the hair is termed the cuticle. The hair shaft has three zones: the outermost zone is the cuticle; the middle zone is the cortex, and the innermost zone is the medulla. The cuticle in hair is the outermost layer of keratinocytes originating from the hair matrix, as seen in a cross-section of the hair bulb. It acts as a protective layer.
The cuticle covers the cortex, which is a layer of compressed, keratinized cells. The internal structure of the hair, including the cortex and medulla, is also determined by the shape of the hair follicle. So, The correct answer is an option A