If the working-age share of a country is declining but total output is increasing, which factor can explain this?

Correct answer: Productivity per worker may be rising

Total output depends on more than the percentage of people in the working-age group. It also depends on how much each worker can produce, the quality of technology and capital, education and skills, organisation, and the number of people who actually participate in work. If these factors improve, each worker may produce more goods or services. As a result, total output can rise even when the working-age share of the population is falling.

Therefore, option A provides a valid explanation: productivity per worker may be increasing. For example, improved machines, training, infrastructure, or work methods can raise output per worker and offset a smaller working-age proportion. Option B is too narrow because population percentages alone do not determine production. Option C is an absolute and inaccurate claim, since some older people may remain economically active. Option D is also wrong because a lower share does not always force output to decline.