Flavonoids are a common component of almost all plants, but a specific variety of flavonoid in apples has been found to be an antioxidant. Antioxidants are known to be a factor in the prevention of heart disease. Which one of the following can be properly inferred from the passage? ['At least one type of flavonoid helps to prevent heart disease.', 'Eating at least one apple each day will prevent heart disease.', 'Flavonoids are essential to preventing heart disease.', 'A diet composed largely of fruits and vegetables will help to prevent heart disease.']