The correct option is "2 and 3 only."

Statement 2 is correct because the Central Ground Water Authority (CGWA) was indeed constituted under the Environment (Protection) Act of 1986 to regulate groundwater management and protect groundwater resources. Statement 3 is also correct as India has the largest area under groundwater irrigation globally, highlighting its crucial role in the country's agriculture and food security. However, statement 1 is misleading; while many districts face groundwater stress, the percentage specified may vary over time and is not uniformly recognized at the level described. Understanding these nuances is important in perceiving India's water resource management challenges, which are critical in the context of sustainable development and agriculture, topics frequently highlighted in UPSC examinations.