Which of the following can be a sign of nutrient deficiency?

Brittle nails and hair loss are common physiological signs that can indicate a nutrient deficiency. These symptoms often arise when the body lacks essential nutrients such as proteins, vitamins, and minerals needed for healthy hair and nail growth. For example, deficiencies in biotin, zinc, and protein can particularly affect hair strength and growth, while calcium and certain B vitamins are crucial for nail health. When the body is deprived of these nutrients, it prioritizes essential functions and might reduce the resources allocated for maintaining hair and nail integrity, leading to brittleness or loss.

The other options describe positive health changes that are unlikely to be associated with nutrient deficiencies. Increased energy levels and enhanced immune response generally suggest that nutritional needs are being met and that the body is functioning optimally. Similarly, improved skin health is associated with adequate nutrition and the presence of essential vitamins and fatty acids, rather than deficiency. Thus, it is clear that brittle nails and hair loss serve as reliable indicators of nutrient deficiency.