The correct answer is sympathetic nervous system.
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The sympathetic nervous system is a component of the autonomic nervous system, together with the parasympathetic system. Their functions are opposite but coordinate to maintain homeostasis. The sympathetic system has a role to control the body's response during perceived threat (fight and flight reactions). According to this, it dilates the pupils, contracts the muscles, increases heart rate...</span>
That answer is A. Hopefully this helps.
The air in Greg's house is like the cytoplasm of a cell because it is the gel-like material that surrounds the other parts of the cell.
Hope this helps! :)