Sustainable development means meeting the needs of the present without compromising the ability of future generations to meet their own needs. Indicators used to measure it must therefore capture environmental health, human well-being, and resource use together, not economic output alone.

The genuine sustainability indicators among the options are:

• Biocapacity — the capacity of an area's ecosystems to produce biological resources and absorb waste; it tells us how much nature is available.
• Human Development Index (HDI) — a composite of life expectancy, education, and per-capita income that measures quality of life rather than just money.
• Ecological Footprint — the demand humans place on nature, measured against how much biocapacity exists; when the footprint exceeds biocapacity, resources are being overused.

Why the Gross Domestic Product (GDP) growth rate is the correct answer (the one NOT typically used): GDP measures only the total monetary value of goods and services produced. It is blind to how that growth is achieved. A country can raise its GDP by cutting down forests, burning fossil fuels, or depleting minerals, while pollution rises and inequality widens. Because GDP growth can increase even as environmental quality and social equity decline, it is not, on its own, a valid measure of sustainable development. The other three explicitly link human activity to ecological limits, which is exactly what sustainability requires.