Why Is It That Population Pyramids for Developed Nations in Particular

Multiple Choice

Why is it that population pyramids for developed nations in particular have changed so drastically over the last 60 years and will continue to do so over the next several decades?

A) ​Because the number of people living to an old age has increased significantly.
B) ​Because the rate of juvenile death due to illness and accident has skyrocketed.
C) ​Because more people are choosing to get married at a later age.
D) ​Because the age at which people are choosing to have children is getting later and later.