The best choice is uneven heat distribution because If a place has a warm are it has low pressure and if it has a cold area it has high pressure.
Wind moves from areas of high air pressure to low air pressure.
Example: Land Breeze and Sea Breeze.
Th earth has uneven distribution due to different angles of insolation and by earth tilts.
The exchange of matter or substances between the cell and its environment is dynamic as it varies in direction and rate as per the requirements of the cell. Thus,a cell attains a stead -state wherein the internal conditions of the cell remain constant. Hence, cell is considered to be a open dynamic system
