"One of the two major systems that are affected by the stress response is the , which results in increased production and/or secretion of corticotrophin-releasing factor, adrenocorticotropic hormone, and cortisol."

The correct answer is the endocrine system.

Explanation:

The sympathetic division of the autonomic nervous system and the endocrine system are the two prime systems that take part in the stress response.  

At the time of acute or chronic stress, the endocrine system first makes the hypothalamus to discharge CRH or corticotropin-releasing hormone into the bloodstream. The release of CRH further makes the anterior pituitary to discharge ACTH or adrenocorticotropic hormone into the blood. This further stimulates the adrenal cortex to discharge cortisol, that is, one of the glucocorticoid hormone into the bloodstream.  

The cortisol finally makes the organs and tissues present within the body to effectively cope up with the initial stress stimulus.  

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

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