Final answer:
The elderly population is increasing most rapidly in high-income nations, leading to significant demographic changes that will impact the economy and social services. The answer is option C.
Step-by-step explanation:
The share of the elderly population is increasing most quickly in high-income nations. As demographics shift, these countries are encountering a growing proportion of older individuals in comparison to younger ones. While low-income nations currently have a larger percentage of youth, they will also experience an increase in their elderly population around 2050.
However, high-income countries are already approaching a demographic scenario where the elderly form a much larger share of the population. This demographic trend is essential to understand as it has significant implications for the economy, industry, and social services within these nations.