Populations of Caribbean coral have decreased significantly over the past 30 years due to disease. Which of the following is most likely a major factor leading to the increased amount of disease in the coral?
A Symbiotic algae are living in the coral cells.
B Several different species of fish live on the coral reefs.
C Levels of spawning have decreased and lowered reproductive rates.
D Water temperatures have increased and favored the growth of microorganisms.