Which of the following is NOT a risk factor for coronary heart disease (CHD)?

High activity level is indeed not considered a risk factor for coronary heart disease (CHD). In fact, regular physical activity is generally associated with a lower risk of CHD. Engaging in physical exercise helps improve cardiovascular health by enhancing lipid profiles, lowering blood pressure, improving insulin sensitivity, and contributing to weight management. It strengthens the heart muscle, promotes healthy blood circulation, and reduces overall inflammation in the body.

In contrast, chronic renal failure is associated with an increased risk of cardiovascular disease due to factors such as fluid overload, electrolyte imbalances, and the presence of inflammation and oxidative stress. Diabetes mellitus is a well-known risk factor for CHD since it can lead to arterial damage and increased rates of atherosclerosis. Elevated homocysteine levels have also been linked to a higher risk of cardiovascular events, as they may contribute to endothelial dysfunction and vascular damage.

Therefore, having a high level of physical activity is inversely related to the risk of developing coronary heart disease, distinguishing it from the other options that are all recognized as significant risk factors.