How does physical activity contribute to chronic disease prevention?

Physical activity is instrumental in the prevention of chronic diseases primarily through its positive effects on cardiovascular health and its role in maintaining a healthy weight. Engaging in regular physical activity enhances heart function, improves circulation, and helps regulate blood pressure and cholesterol levels. These factors significantly reduce the risk of cardiovascular diseases, such as heart attacks and strokes.

Furthermore, physical activity plays a crucial role in weight management. By burning calories and increasing metabolism, it helps individuals achieve and maintain a healthy weight, thereby reducing the risk of obesity-related conditions, including type 2 diabetes and certain cancers. Regular exercise also contributes to better insulin sensitivity, which is another critical factor in chronic disease prevention.

In contrast, the other options present scenarios that do not align with the benefits of physical activity. Decreasing muscle strength, increasing the risk of obesity, and promoting a sedentary lifestyle are all contrary to what regular physical activity achieves. Therefore, option B accurately reflects the relationship between physical activity and chronic disease prevention.