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

Explanation

Coral bleaching occurs when corals expel the symbiotic algae (zooxanthellae) living in their tissues due to environmental stress, primarily caused by rising sea temperatures.

In the Andaman and Nicobar Islands, the primary cause of catastrophic coral bleaching and mass coral deaths has been the increase in sea surface temperature, particularly during marine heatwaves and El Niño events.

Industrial activities in coastal regions and heavy marine pollution can degrade coral reefs but are not the primary causes of mass bleaching.

A decrease of temperature by 4° C is unlikely, as corals thrive in warm tropical waters and are more sensitive to excessive heat rather than extreme cooling.