Final answer:
The correct answer to the question is d. 2050, which is the year by which those over the age of 65 are projected to outnumber those under 5 globally. This is part of a broader trend of an aging global population, with significant implications for society and policy.
Step-by-step explanation:
In a broader context, the implications of these shifts are substantial. Many high-income nations are already on the path where the elderly (over 65) will form a larger share by around 2020. However, the global demographic change, where the elderly will outnumber the young under five years old globally, is projected for the year 2050. This phenomenon is referred to as "the graying of America" and reflects an increase in the proportion of the senior population worldwide, which is largely attributed to improved life expectancy and lower birth rates. By 2019, there were around 703 million people aged 65 or over worldwide, and this figure is expected to double to 1.5 billion by 2050, making up one in six people on the planet.
The tripling of the senior population over the past century in the U.S., as well as the drop in the proportion of young children, is indicative of the transformations in age demographics. These shifts have implications for major policy decisions and day-to-day life, as they affect everything from healthcare systems to economic structures.