Answer:
The correct answer is B.
Step-by-step explanation:
Many industrialized countries are seeing an aging of their populations.
This change in their demographic is being caused by the fertility rate falling below the replacement rate.
Socially, people are starting to have children later in their life, and the average number of children per couple is less than two.
On the other hand, longevity has improved, allowing people to live longer thanks to all the medical advancements.