Involves comparing the costs and benefits of consuming or producing one additional unit of a good or service.

volcanoes (an event in the geosphere) release a large amount of particulate matter into the atmosphere. these particles serve as nuclei for the formation of water droplets (hydrosphere). rainfall (hydrosphere) often increases following an eruption, stimulating plant growth (biosphere).

because the light is a great source of energy for the plants to survive. (i hope this )