Concept:The deep or profundal zone of an aquatic habitat receives little or no sunlight, so it supports very few organisms.
Explanation:The zone labelled III is the deep or profundal zone.
Sunlight hardly reaches this depth.
Without light, photosynthesis cannot take place.
This limits the availability of oxygen and food.
Only a few adapted organisms, such as some decomposers, can survive there.
Therefore, very few organisms are found in zone III.
Answer:C. III
