Answer:
The lack of sunlight in the deep ocean limits the types of organisms that can survive.
Explanation:
Limiting factors are biotic or abiotic environmental factors that limit the distribution of organisms in that an environment. The factor varies from environment to environment, habitat to habitat and biome to biome.
Oxygen level, temperature, salinity and light are indeed some of the abiotic factors limiting the distribution of organisms in the seas/oceans.
However, oxygen levels in deep ocean cannot be too high for organisms to survive, and while variation in temperature do exist between shallow and deep ocean, it is never to the point of freezing. Also, while salinity do limit the distribution of organisms in the ocean, no part of the ocean is too salty for marine organism.
The major limiting factor is light. While the shallow end of the ocean is adequately illuminated to sustain photosynthetic and other diverse forms of organisms, the deep end is occupied by less diverse organisms that have developed necessary adaptation to low light.