A volcanic eruption releases gases from the geosphere into which spheres, affecting multiple systems?

• A. The atmosphere and hydrosphere only.
• B. The biosphere only.
• C. The atmosphere, biosphere, and hydrosphere.
• D. The geosphere only.

Answer: (C)

Gases released from the geosphere during a volcanic eruption move into neighboring systems, affecting multiple spheres. The atmosphere receives the immediate emissions—water vapor, carbon dioxide, sulfur dioxide, and other gases—that change air chemistry and can influence climate and air quality. Some of these gases dissolve into the hydrosphere, affecting oceans, rivers, and lakes by altering pH and chemistry and potentially harming aquatic life. In the biosphere, living organisms respond to shifts in atmospheric composition, air quality, and the downstream effects on water and habitats; plants rely on CO2 for photosynthesis but excessive or toxic gases can be detrimental, and animals are affected by polluted air and altered ecosystems. Because volcanic emissions touch all three spheres, the best answer includes the atmosphere, biosphere, and hydrosphere. Choices that mention only one sphere miss the broader impact on the other systems.