Which of the following is one of the major health risk factors?

Smoking is recognized as a major health risk factor due to its association with a variety of serious health issues including cardiovascular disease, respiratory illness, and various forms of cancer. The detrimental effects of smoking extend beyond the individual smoker, as it contributes to secondhand smoke exposure which poses risks to non-smokers. The extensive body of research linking smoking to poor health outcomes emphasizes its role as a significant lifestyle choice impacting overall health.

While options like obesity and depression can also be significant health risk factors that affect well-being, smoking's pervasive risks and its role in the prevention of many diseases make it a crucial factor in discussions about health risks. Allergies, on the other hand, typically do not have the same profound long-term health consequences as smoking and thus are not grouped alongside major health risk factors like smoking, obesity, and serious mental health conditions.