What is the most likely cause of the coral bleaching shown below?

In general, how long does it take to accomplish a long-term goal? a.a few days to a weekb.a few weeks to a monthc.a few months to a yeard. more than a year

What percentage of light hits earth's surface directly?

Is there any species that went extinct in recent years due to natural causes (not caused by human interaction). if so, what caused it?