Sustainable development in policy terms is about balancing three key elements—economic growth, social equity, and environmental protection—so that present needs are met without compromising the ability of future generations to meet theirs. The best description captures this balance and the idea of planning for long-term outcomes, not just short-term gains, by promoting growth that is fair and environmentally sound. In practice, this means using resources efficiently, investing in education and health, reducing pollution, protecting ecosystems, and ensuring that economic benefits are shared fairly. Why this fits: it explicitly includes meeting present needs while safeguarding the options of future generations, and it ties together economic, social, and environmental goals rather than focusing on just one aspect. The other ideas fall short because focusing only on economic growth ignores social and environmental costs; ignoring environmental concerns leads to degradation and loss of resources; and development without planning ignores long-term viability and can create problems that undermine future well-being.