Which of the following is a major risk factor for dyslipidemia?

Smoking is indeed a major risk factor for dyslipidemia. Dyslipidemia refers to an abnormal amount of lipids in the blood, which is a crucial factor in the development of cardiovascular disease. Cigarette smoking negatively impacts lipid profiles by lowering high-density lipoprotein (HDL) cholesterol, which is often referred to as "good" cholesterol. Lower levels of HDL are associated with an increased risk of atherosclerosis and heart disease. In contrast, smoking can contribute to higher levels of low-density lipoprotein (LDL) cholesterol and triglycerides, further compounding the risk for cardiovascular complications.

The other scenarios mentioned, such as low cholesterol, daily exercise, and a high-fiber diet, are generally protective against dyslipidemia rather than risk factors. Low cholesterol levels can indicate good health, while daily exercise and high-fiber diets are associated with improved lipid profiles and reduced cardiovascular risk. Thus, smoking stands out as a significant lifestyle-related risk factor that adversely affects lipid levels in the body.