In Citizens United v. FEC, the Supreme Court ruled that a. corporations and unions can spend unlimited amounts on campaigns.
b. corporations and unions are allowed to coordinate with candidates.
C. corporations and unions cannot donate money on campaigns.
d. campaign contributions are not protected by the First Amendment.

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