Final answer:
Cardiovascular disease is the leading cause of death in the U.S. and most developed countries due to factors such as a sedentary lifestyle and poor diet.
Step-by-step explanation:
The leading cause of death in the U.S. and most developed countries is cardiovascular disease. This class of diseases affects the heart and blood vessels and includes conditions such as coronary artery disease and stroke. A sedentary lifestyle, high trans-fat diets, smoking, obesity, diabetes, high blood cholesterol, and lack of exercise are major risk factors. While cancer does cause a significant number of deaths and has a major impact on health, cardiovascular disease is recognized as the top cause of mortality globally. By modifying risk factors through lifestyle changes and medications, the incidence of cardiovascular disease can often be reduced.