What was the meaning is all of the event referred to in this headline

Migration the ability to meet current needs without reducing the ability to meet future needs 2. immigration the leaving of one's homeland to settle in a new place 3. migration a situation in which the birth rate is not sufficient to replace the existing population 4. overpopulation the movement of people to a new country 5. sustainable development the increase in the population of a city 6. underpopulation a situation in which resources are being used up at a faster rate than they can be replenished 7. unsustainable development a situation in which the number of people exceeds the available natural resources in an area 8. urbanization the movement of people from one place to another