The number of elderly people is rising rapidly in a country, but the old-age dependency ratio remains nearly stable. What is the most likely explanation?

Correct answer: The working-age population is also growing at a similar rate

The old-age dependency ratio compares the number of older people with the working-age population. It is a relative measure, not a count of elderly people alone. The absolute number of older people can increase rapidly while the ratio remains almost unchanged if the working-age population also grows at a similar rate. In that situation, both the numerator and denominator rise together, so their relationship changes little.

Option A therefore gives the most likely explanation. For instance, migration, earlier population growth, or the movement of large cohorts into working ages could enlarge the working-age group alongside the elderly group. The ratio would not necessarily rise simply because the elderly count increased. Option B is impossible as a general explanation because children can exist even when elderly numbers rise. Options C and D use unsupported absolute claims. The important lesson is to distinguish population totals from ratios.