为什么移民不对

问题如下：

Which of the following are social megatrends?

选项：

A.Urbanization and mass migration

B.Changing demographics and urbanization

C.Changing demographics and mass migration

解释：

B is correct because social megatrends are long-term social changes that affect governments, societies and economies permanently over a long period of time. These include changing demographics, including health and longevity, and urbanization.

A and C are incorrect because some environmental megatrends have a severe social impact as well. These include mass migration.