The Ratio of the Number of People in the Population

The ratio of the number of people in the population aged 65 and older to the number of people aged 20 to 64 has risen in most of the developed countries as:

A) longevity has declined and the families have had many children.
B) the family planning laws have been relaxed.
C) birth rates have increased over time.
D) there has been an increased preference for male child.
E) longevity has increased and the families have had fewer children.