What is a key responsibility of the Centers for Disease Control and Prevention (CDC)?

The key responsibility of the Centers for Disease Control and Prevention (CDC) involves studying diseases and providing guidance to prevent their spread. This encompasses a broad range of activities aimed at public health, including conducting research on various diseases, tracking outbreaks, and developing strategies to reduce transmission. The CDC's role is pivotal in enhancing community health by offering evidence-based recommendations and guidelines that inform both health professionals and the public on effective disease prevention and control measures.

The other options do not align with the primary mission of the CDC. For instance, monitoring cosmetic sales and regulating skin care products are under the purview of organizations like the Food and Drug Administration (FDA), not the CDC. Basic first aid training is typically provided by organizations such as the American Red Cross or other emergency response bodies. Therefore, the emphasis of the CDC's work on disease research and prevention is what makes it the correct choice in this context.