Identify three indicators of sustainable development and explain their relevance.

• A. Ecological footprint per capita; Water Quality Index; Renewable energy share of total energy consumption.
• B. GDP per capita; Unemployment rate; Population growth.
• C. Number of parks; Forest area; Road density.
• D. Soil pH; Nitrate concentration; Drainage rate.

Answer: (A)

Sustainable development indicators should reflect environmental health, resource use, and progress toward a cleaner, more resilient energy system. Ecological footprint per capita shows how much of Earth's resources each person consumes relative to what the planet can renew, highlighting whether a society is operating within ecological limits. Water quality index measures the condition of water bodies, capturing ecosystem health and the safety of drinking water and aquatic life—a direct read on environmental integrity. Renewable energy share of total energy consumption indicates how much of the energy mix comes from sustainable sources, pointing to progress in reducing pollution and greenhouse gas emissions.

Other options mix broader economic metrics (like GDP per capita, unemployment, and population growth) or environmental features that don’t by themselves indicate sustainability outcomes, or focus on soil and hydrology details rather than overall sustainable development progress. The trio above ties environmental pressure, resource health, and energy transition into a cohesive picture of sustainability.