Which of the following does volcanic gas emission directly contribute to? photosynthetic illumination ocean anoxia land formation exoskeletal development

Volcanic gas emissions can directly contribute to ocean anoxia. Volcanic gases, such as sulfur dioxide (SO2), can react with water vapor in the atmosphere to form sulfuric acid (H2SO4). This acid can then fall to the ocean as acid rain, which can lower the pH of the water and reduce the amount of dissolved oxygen available for marine life. This can lead to ocean anoxia, which is a condition where the oxygen levels in the water are too low to support most marine life. The other options, photosynthetic illumination, land formation, and exoskeletal development, are not directly influenced by volcanic gas emissions.