Which of the following is a primary risk factor for developing lung cancer?

Smoking is recognized as the primary risk factor for developing lung cancer. This association is supported by extensive research that demonstrates a strong link between tobacco use and the incidence of lung cancer. Smoking introduces numerous carcinogens into the lungs, which can lead to genetic mutations and cellular changes that promote cancerous growth.

In contrast, while other risk factors such as exposure to sunlight (which is primarily linked to skin cancer), high-fat diet (often associated with various types of cancer but not specifically lung cancer), and family history of breast cancer are relevant in their contexts, they do not have the same level of direct correlation with lung cancer risk as smoking does. The overwhelming majority of lung cancer cases are attributed to the inhalation of tobacco smoke, making it a key focus of prevention and public health campaigns aimed at reducing the incidence of this disease.