The reason (s) for the rising proportion of elderly people in virtually all industrialized societies is (are) :

A) fertility rates have been declining
B) population growth has slowed
C) medical advances have been made
D) better welfare provisions are available
E) all of these choices

The rising proportion of elderly people in virtually all industrialized societies is a result of multiple factors. Fertility rates have been declining, which means fewer children are being born to replace older generations. Additionally, population growth has slowed in these societies, resulting in a larger portion of elderly individuals in the overall population. Medical advances have also been made, which allow people to live longer lives. Finally, better welfare provisions are available, which can also contribute to longer lifespans and a larger elderly population. Therefore, all of these choices (A-E) are correct.