Explanation:

Demographic dividend refers to the economic growth potential that can result from shifts in a population's age structure, mainly when the share of the working-age population is larger than the non-working-age share. The working-age population is typically defined as 15 to 64 years, or in some contexts, 15 to 59 years. Option (d) 'Working population of 15 to 59 years' is the most appropriate definition among the given choices.