Question

aging populations can be a problem for developed countries because
there are fewer younger workers coming into the workforce.
most older workers demand top - level pay and full benefits.
many older people are skilled in manufacturing, not technology.
younger workers cannot find jobs when older people work longer.

Explanation:

Aging populations lead to fewer younger workers entering the workforce. This can cause labor shortages, reduced economic growth potential, and strain on social security systems as there are fewer workers to support retirees. Older workers' pay demands (second option) are not the main systemic problem. Skill differences (third option) are not the core issue. And while older workers working longer might seem to affect younger workers' job access, the fundamental problem is the overall decline in the young - worker labor - force entry (fourth option is a less central and more nuanced aspect compared to the first).

Answer:

there are fewer younger workers coming into the workforce.