A research team recruited 53 healthy volunteers between the ages of 45 and 64 to participate in a two-year exercise program. It was found that volunteers' cardiac health indicators, especially left ventricular function, improved correspondingly. This is Because the left ventricle can pump oxygen-rich blood into the aorta to supply systemic organs. Lack of exercise and aging of the organs can weaken the left ventricular muscles. The research team believes that proper exercise can help reverse the damage caused by myocardial aging and reduce Heart attack risk. Which of the following, if true, best supports the above conclusion? ['The younger you start exercising, the lower your risk of a heart attack.', 'Appropriate exercise helps increase oxygen intake and enhance metabolic capacity.', 'People with a history of heart disease have noticeably improved heart function after proper exercise.', 'Most middle-aged and elderly people with left ventricular muscle sclerosis have insufficient daily exercise.']