Which of the following is NOT a risk factor for coronary artery disease (CAD)?

The correct choice is C, outdoor exercise, because it is associated with numerous health benefits, particularly for cardiovascular health. Engaging in outdoor exercise can help lower blood pressure, improve cholesterol levels, and reduce the risk of obesity, all of which are factors that contribute positively to heart health. It can also enhance overall well-being and increase physical fitness, in contrast to the other options.

Hypertension, hyperlipidemia, and smoking are established risk factors for coronary artery disease. Hypertension contributes to the development of atherosclerosis, which narrows the arteries and decreases blood flow. Hyperlipidemia, characterized by high levels of lipids in the blood, also plays a critical role in the buildup of plaque in the arteries. Smoking is well-documented as a significant risk factor because it damages the lining of blood vessels and promotes plaque buildup, increasing the risk of heart attacks and other cardiovascular events.

Therefore, outdoor exercise stands out as a protective factor rather than a risk factor for coronary artery disease.