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>
x or y because both can cause it
Because the majority of cell differentiation occurs during the EMBRYONIC phase, .................. The embryonic stage of pregnancy is the period after implantation during which all the important organs and structures in the growing fetus is formed. Tetratogens are factors that caused malformation of embryo. Exposure to tetratogens during embryonic stage cause most destructive damages.