Answer :
The highest organic carbon content on the ocean floor at 3000m deep is likely under the Antarctic Ice shelf in the winter due to the formation and flow of Antarctic Bottom Water, which carries and deposits dissolved CO2 into the deep ocean. So, the correct option is D. Under the Antarctic Ice shelf in the winter.
The location that will generally have the highest organic carbon content at the bottom of the ocean, assuming each region is roughly 3000m deep, is Under the Antarctic Ice shelf in the winter. This is because most of the transport into the deep ocean takes place in the Weddell Sea off the coast of Antarctica. The formation of Antarctic Bottom Water (AABW) in these polar regions involves the sinking of cold, oxygen-rich water to the bottom that brings dissolved CO2 and other gases along with it into the deep ocean. This AABW is a major route by which dissolved CO2 accumulates in the deep ocean where it can stay for thousands of years, which contributes to the organic carbon content on top of the sediment in these regions.
Moreover, cold bottom waters can hold more dissolved gases, and high pressures increase gas solubility, adding to the higher CO2 concentration in the water. Since the deep ocean waters of the Antarctic are cold and have high solubility for gases, more organic carbon content can accumulate here. Additionally, this water mass can be traced into all three oceans, indicating a wider influence on the global deep water carbon content. So, the correct option is D. Under the Antarctic Ice shelf in the winter.
