Read the text. Choose the best word that fits the space.

Water pollution is also a growing concern in Russia. Industrial waste, agricultural runoff, and untreated sewage frequently pollute rivers, lakes, and coastal areas. The Volga River, the longest river in Europe, is one of the most polluted water bodies in the country due to waste from nearby industries and municipalities. In addition, the Aral Sea—which Russia shares responsibility for with Kazakhstan—has almost completely dried up due to 4. ______ water management practices, leaving behind toxic desert landscapes.

• unsustainable
• unclear
• sparkling
• drinkable