Which of the following have coral reefs? 1. Andaman and Nicobar Islands 2. Gulf of Kachchh 3. Gulf of Mannar 4. Sunderbans Select the correct answer using the code given below.

1. Andaman and Nicobar Islands: This region hosts some of India's richest coral reefs, including extensive fringing reefs, some barrier reefs, and atoll reefs (like those in Lakshadweep). They have high biodiversity. Correct. 2. Gulf of Kachchh: Located in Gujarat, this area has coral reefs, primarily patchy reefs and fringing reefs around numerous islands within the Marine National Park (e.g., Pirotan Island). These reefs exist under relatively harsh environmental conditions (high salinity, temperature fluctuations). Correct. 3. Gulf of Mannar: Situated between India and Sri Lanka, the Gulf of Mannar Biosphere Reserve contains significant fringing reefs around a chain of 21 islands. Correct. 4. Sunderbans: This is the world's largest deltaic mangrove ecosystem, located in the Bay of Bengal. The environment here is characterized by high sediment load, high turbidity, and significant freshwater influx from the Ganges-Brahmaputra river system. These conditions are generally unsuitable for the growth of coral reefs, which require clear, saline water. Incorrect. Therefore, coral reefs are found in the Andaman and Nicobar Islands (1), Gulf of Kachchh (2), and Gulf of Mannar (3).