Which of the following is a significant risk factor for cardiovascular diseases?

Smoking is recognized as a significant risk factor for cardiovascular diseases due to its detrimental effects on vascular health. It contributes to the development of atherosclerosis, which is the buildup of plaques in the arteries, leading to narrowed arteries and increased risk of heart attacks and strokes. Additionally, smoking can cause inflammation and damage to blood vessels, further compromising cardiovascular function.

In contrast, excessive physical activity does not typically pose a risk to cardiovascular health; rather, it is often associated with improved cardiovascular fitness when done in moderation. Low blood pressure is usually considered a favorable condition, associated with a lower risk for heart disease, provided it is not associated with significant symptoms or conditions. Similarly, low cholesterol, particularly low levels of LDL cholesterol, is generally seen as protective against cardiovascular diseases.