Which of the following is a cause of coronary heart disease?

• A. Narrowing of the coronary arteries
• B. Regular exercise
• C. Low blood pressure
• D. Adequate sleep

Answer: (A)

Coronary heart disease is caused when the arteries that feed the heart become narrowed, usually by a buildup of fatty plaque inside the vessel walls (atherosclerosis). This narrowing reduces the flow of oxygen-rich blood to the heart muscle, which can lead to chest pain and, if severe, a heart attack, especially during exertion when the heart needs more oxygen. The other options describe factors that help protect the heart or are not a cause: regular exercise lowers risk and improves heart health, adequate sleep supports cardiovascular function, and low blood pressure is not a cause of CHD (high blood pressure is the more relevant risk factor).