Raising retirement age expands the workforce

Steps:

• Raising retirement age means people work longer before retiring.
• This keeps more older individuals in the labor force.
• The working-age population grows as retirees delay leaving work.
• Overall, economic dependency ratio improves with more workers.

Why D is correct:

• By definition, the working population includes those employed or seeking work up to retirement age; extending it directly increases this group's size.

Why the others are wrong:

• A: No direct link to immigration; policy targets domestic workforce, not migration.
• B: Reduces government spending on pensions by delaying payouts, not increasing it.
• C: Lowers pension spending as fewer people retire earlier and draw benefits.

Final answer: D