The hypothalamus activates the adrenal-cortical system by releasing ________, which signals the pituitary gland to secrete ________, the body's "major stress hormone."

A) cortisol; adrenaline
B) corticotropin-release factor; adrenaline
C) cortisol; adrenocorticotropic hormone
D) corticotropin-release factor; adrenocorticotropic hormone

The hypothalamus releases corticotropin-releasing factor (CRF), which signals the pituitary gland to secrete adrenocorticotropic hormone (ACTH), leading to the release of cortisol from the adrenal cortex. Therefore, option D is the best choice. Option A is incorrect because cortisol is released by the adrenal cortex, not adrenaline. Option B is incorrect because CRF signals the pituitary gland to secrete ACTH, not adrenaline. Option C is incorrect because cortisol is released in response to ACTH, not directly from the hypothalamus.