Which condition does not prevent nail growth?

Nail growth is influenced by various factors, including overall health, nutrition, and physical activity. Exercise plays a critical role in promoting good circulation, which helps deliver essential nutrients and oxygen to the nails and surrounding tissues. Additionally, regular movement can stimulate the metabolism and improve the health of cells, contributing to better nail growth.

In contrast, conditions such as a poor diet can lead to nutrient deficiencies, affecting the growth and strength of nails. Insufficient physical fitness may impact overall health, which can also contribute to weaker nails. Hang nails, being a condition that affects the cuticles and surrounding skin, can lead to pain or inflammation that may impede normal nail growth or increase the risk of nail-related issues.

Therefore, exercise is beneficial for promoting healthy nail growth and does not prevent it, making it the correct choice in this context.