A recent study found that regular drinking of yogurt reduces the risk of tooth decay in children. Prior to this, researchers also suggested that yogurt can prevent tooth decay in children, and studies have shown that butter, cheese and milk have no obvious effect on preventing tooth decay. Although drinking more yogurt has a protective effect on children's teeth, the reason why yogurt can reduce the risk of tooth decay is still unclear. At present, it is said that the protein contained in yogurt has adhered to the tooth surface, thereby preventing harmful acids from attacking the teeth. Which of the following, if true, would best support this research finding? ["The protein content of butter, cheese and milk is not as rich as that of yogurt, and it is not obvious in children's teeth.", "The enamel of children's gums is in the immature stage, and its ability to resist acid corrosion is low. Artificial sugared yogurt will increase the risk of tooth decay.", 'Studies have shown that children who eat yogurt at least 4 times a week can reduce the incidence of tooth decay by 15%.', 'The world is where scientists from many countries are studying the role of yogurt in preventing tooth decay in children.']