Correct Response: A. Primary productivity of the Arctic Ocean increases during summer as warming temperatures melt sea ice, allowing sunlight to penetrate surface waters. The increased light stimulates growth of phytoplankton, triggering a rapid increase in primary productivity. Primary productivity is affected by the availability of sunlight, carbon dioxide, and nutrients, but nutrients from snowmelt are not a critical factor in the seasonal increase in primary productivity (B) in this region. Although upwelling of nutrient-rich deep water does bring essential nutrients to the surface (C), it primarily occurs in a small area of the Beaufort Sea in the Arctic Ocean and is not a critical component of the phytoplankton growth that increases primary productivity throughout the Arctic Ocean. Wind- driven oxygenation of Arctic Ocean surface waters (D) is also not a critical component of summer increases in the primary productivity of the Arctic Ocean.
