an experiment showed that the growth of a pillar coral decreased in warm water in which other organisms blocked sunlight. which conclusion can be made based on these data?

Sunlight is very essential for the growth of corals and thus they grow in shallow water. zooxanthellae (algae) growing inside the corals to produce oxygen and other things which are essential for the growth of corals as well. Since sunlight is essential for zooxanthellae. corals also need sunlight to survive.