Necessary conditions: When one thing condition M does not exist, the other thing condition N must not exist, then the former (M) is a necessary condition for the latter (N). According to this definition, in the following, which of the following is the necessary condition relationship between M and N? ['A number is divisible by 2 (M), and the number is even (N).', 'A major safety responsibility accident (M) occurred, and casualties (N).', 'Good family education (M), child success (N).', 'A country is rich in natural resources (M) and its economy is developed (N).']