How does broad-spectrum sunscreen protect the skin?

Broad-spectrum sunscreen is designed to protect the skin from both UVA and UVB rays, which are two types of ultraviolet radiation emitted by the sun that can cause skin damage. UVB rays are primarily responsible for causing sunburn, while UVA rays penetrate deeper into the skin and are associated with skin aging and the development of skin cancer.

When a sunscreen is labeled as "broad-spectrum," it means it has been tested and shown to provide adequate protection against both types of rays. This dual protection is crucial for minimizing the risk of skin damage and skin cancer, making broad-spectrum sunscreens an essential part of effective sun protection practices.

The other options do not accurately represent the full capability of broad-spectrum sunscreens. For instance, protecting only against UVB rays would leave the skin vulnerable to UVA damage, while statements regarding prevention of sunburn only or darkening the skin do not accurately describe the protective function of such sunscreens.