A high proportion of dependent age groups can place greater pressure on what?

Correct answer: Working-age population

Dependent age groups usually include children and older people who are less likely to earn regular income. They still need food, housing, education, health care, protection, and sometimes pensions or daily assistance. When their share becomes large, fewer working-age people may have to support more dependents through household income, taxation, public services, or care work. This can raise the dependency burden on workers and governments.

The pressure is not placed on ocean currents, mineral reserves, or rainfall systems, because those are physical or environmental features rather than providers of support. The exact burden depends on employment, productivity, family arrangements, and public policy, but the main population relationship remains clear. Thus option A, the working-age population, is the correct choice.