Answer: a. The oceans have a significant impact on the levels of atmospheric gases.
Oceans acts a carbon sink or reservoir. Ocean fixes atmospheric carbon in water which is required for life processes in oceanic water body. Carbon dioxide from the atmosphere dissolves in the surface waters of the ocean. The carbon dioxide from the water is taken up by aquatic plants to conduct photosynthesis. Many aquatic animals use this form of carbon to make their shells and skeletons. Also, the dead and decaying plants and animals are deposited at the bottom of the oceanic bed this results in formation of oceanic organic matter a rich source of carbon. These sediments are again exposed to upper superficial layers of oceanic water, hence becomes available to plants for photosynthesis. Therefore, oceans are fixing atmospheric carbons, hence limiting the levels in the atmosphere.
