If a country has a low child share and a very high working-age share, but fertility remains very low for the next 25 years, what is the long-term risk?

Correct answer: Future shortage of working-age entrants and rapid growth in old-age dependency

A very large working-age group can provide a temporary demographic dividend, but it is not permanent. If fertility remains very low, each new generation contains fewer children and therefore fewer people who will later enter the labour force. As the current large cohort grows older, the number of older dependants rises while replacement workers become fewer.

Option A states both parts of the long-term risk: a shortage of new working-age entrants and faster growth in old-age dependency. The child share will not necessarily keep rising, and elderly people will not fall to zero. The working-age share can decline after the present advantage passes. Migration, productivity and later changes in fertility may modify the outcome, but they do not remove the demographic logic.