As big as it is, the ocean is nutrient-limited. If you wanted to investigate this phenomenon, one reasonable approach would be to _____.A) compare nutrient concentrations between the photic zone and the benthic zone in various marine locations.B) observe Antarctic Ocean productivity from year to year to see if it changes.C) contrast nutrient uptake by autotrophs in marine locations that are different temperatures.D) experimentally enrich some areas of the ocean and compare their productivity to that of untreated areas.E) follow whale migrations in order to determine where most nutrients are