Acell is a complex system. like most systems, a cell contains a boundary that separates things that are inside the system from those that are outside of the system. which part of the cell functions as a system boundary

answer; polycythemia is the correct answer;

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).