According to a survey by the health department of a country, the incidence of cardiovascular and cerebrovascular diseases in urban residents is nearly three times that in rural areas. Some people claim that this is due to the high fat, high protein, and high-calorie food intake of people in cities. It is said that few people in the countryside have the conditions to have this kind of "rich disease". In fact, this view is difficult to establish, because it ignores the fact that the current life expectancy in cities is higher than 70 years, and that in rural areas is less than 50 years. Which of the following, if true, can best strengthen the above rebuttal? ['Statistics show that patients with cardiovascular and cerebrovascular diseases are currently younger.', 'Statistics show that patients with cardiovascular and cerebrovascular diseases are relatively concentrated in the middle-aged and elderly age group, that is, those over 45 years old.', 'Compared with rural people, urban people have more common knowledge and better medical conditions for preventing and treating cardiovascular and cerebrovascular diseases.', 'Roughly speaking, the longer a person lives, the higher the probability that he or she will get a disease in his lifetime.']