What is occurring when coral reefs are said to be in danger of extinction due to pollution?

The situation described indicates that coral reefs are facing extinction risks specifically due to pollution, which leads to a decline in their habitat quality. The correct response points to the rising ocean temperatures as being a significant factor affecting coral habitats. Elevated temperatures can lead to coral bleaching, a process where the symbiotic algae living within coral tissues are expelled. This not only disrupts the energy supply for the coral but also diminishes its color and resilience against disease and environmental stresses.

Coral reefs rely on stable and specific temperature ranges to thrive. As ocean temperatures rise, they can become less hospitable for coral species, which are sensitive to even slight temperature fluctuations. When combined with pollutants, such as excess nutrients or toxins, this can further accelerate the decline of coral systems, rendering them more vulnerable to extinction.

On the other hand, the options that suggest adaptation, increased reproduction, or abundance in polluted waters do not align with the realities faced by coral ecosystems under stress from pollution and climate change. Coral reefs do not adapt well to rapid changes in temperature, are unlikely to reproduce efficiently under these conditions, and generally do not thrive in polluted environments.