Which of the following reasons caused catastrophic coral bleaching and mass coral deaths in the Andaman and Nicobar Islands ?

The catastrophic coral bleaching in the Andaman and Nicobar Islands, particularly noted in 2024, was primarily caused by a significant rise in Sea Surface Temperatures (SST). According to the Zoological Survey of India (ZSI), temperatures in the Andaman Sea reached approximately 31°C to 32°C, which is about 2°C above the normal threshold for these reefs. Corals maintain a symbiotic relationship with zooxanthellae algae; when water temperatures rise excessively (thermal stress), corals expel these algae, leading to bleaching and eventual death if the heat persists. While industrial activities and pollution (Options A and C) are localized stressors, they are not the primary drivers of regional mass bleaching events. A decrease in temperature (Option D) is contrary to the observed phenomenon of marine heatwaves caused by global warming.