Buildup of material on the inner walls of the ___________________ reduces blood flow to the heart muscle and may cause a heart attack.

The buildup of material on the inner walls of the coronary arteries directly affects blood flow to the heart muscle. The coronary arteries are responsible for supplying the heart with oxygen-rich blood. When there is a buildup of materials such as plaque, which consists of fat, cholesterol, and other substances, it narrows the arteries and restricts blood flow. This condition is known as atherosclerosis. If the blood flow is significantly reduced or blocked, it can lead to angina (chest pain) or a heart attack, as the heart muscle becomes deprived of the necessary oxygen and nutrients needed to function effectively.

The other options pertain to different structures in the circulatory system; the left ventricle is a chamber of the heart that pumps blood to the body, the pulmonary arteries carry deoxygenated blood from the heart to the lungs, and the aortic arch is the section of the aorta that curves between ascending and descending portions. None of these directly supply blood to the heart muscle itself, which is the critical aspect involved in heart attacks caused by reduced blood flow.