What happens when a volcano erupts (sphere interaction)?

• A. The atmosphere releases gases into the geosphere and affects the biosphere and hydrosphere.
• B. The geosphere releases gases into the atmosphere and affects the biosphere and hydrosphere.
• C. The biosphere releases gases into the hydrosphere.
• D. The hydrosphere releases gases into the atmosphere.

Answer: (B)

When a volcano erupts, gases stored in the geosphere (in magma and the surrounding rock) are released into the atmosphere. This makes the geosphere the source of the gases, and once they reach the air they can influence the biosphere (through changes in air quality and climate) and the hydrosphere (via acid rain and altered water chemistry). The other options describe the gas source incorrectly or imply the wrong direction of transfer (air or living systems releasing gases into Earth or water), which isn’t what happens during an eruption.