The increase in the elderly population can largely be attributed to what factor?

The correct answer highlights that advancements in healthcare and longevity have significantly contributed to the increase in the elderly population. Over the years, medical innovations, improved public health measures, better nutrition, and access to healthcare have all played a crucial role in increasing life expectancy. As a result, more individuals are living longer lives, which naturally leads to a growing elderly demographic.

In this context, while decreased birth rates, migration trends, and changes in family structure can influence population dynamics, they do not primarily account for the dramatic rise in the elderly population seen in many countries. The notable improvements in healthcare that have reduced mortality rates and enhanced quality of life for older adults are the key factors driving the increasing number of elderly individuals.