What is a direct cause of coral bleaching?

a)
exposure to sunlight
b)
the loss of symbiotic algae
c)
overgrazing by fish
d)
exposure to transport vessels
e)
all of the above

B) the loss of symbiotic algae

Explanation:

The coral polyps lives in symbiotic association with the algae zooxanthellae. The presence of algae over the coral reefs is necessary for the calcification of the coral skeletons. It is necessary for the health of the reef and the coral. In certain unfavorable marine environmental conditions the bleached corals will expel out the algae. The algae also imparts color to the coral reefs in the absence of the algae the coral reef get bleached or devoid of any color.

Option B: The loss of symbiotic algae

Explanation:

I got it right lol

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the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.