Question: The diagram shows a sketch of fish with the label "respiration". What does the label mean? Question options: Respiration refers to fish performing nitrogen fixation as part of their metabolic pathway. It results in the release of nitrates to the water column at the same time that it removes carbon in the form of methane. Respiration refers to fish eating carbohydrates and obtaining dissolved oxygen as part of their metabolic activity. It results in the release of carbon dioxide to the water column. Respiration refers to fish performing photosynthesis as their metabolic pathway. It results in the release of dissolved oxygen gas to the water column and removes carbon dioxide. Respiration refers to fish performing chemosynthesis as their metabolic pathway. It results in the release of methane as well as removal of carbon dioxide from the water column.