Three causes of coral reef destruction are rising water temperatures land-based pollutants drought conditions too many fish overfishing

option A rising water temperatures  

option B land-based pollutants

option D fish overfishing

Explanation:

Due to rising temperature, bleaching of corals occur. Algae’s produce food for the corals and also  give beautiful colors to it. Due to rise in temperature these algaes are driven out of the corals or they die there by causing bleaching of corals.

Over fishing in coral reefs causes death of other microorganism including  the fish as fishing practices in coral reef involves use of harmful chemicals such as cyanide which is detrimental to all the organsims residing in coral reef.

Land pollutants (both organic and inorganic) disturbs the natural ecosystem of the corals and thus causes its destruction.

Therefore, Option A, B and D are correct