Which hormone does the pituitary gland release in response to signals from the hypothalamus?

The pituitary gland releases adrenocorticotropic hormone (ACTH) in response to signals from the hypothalamus, specifically when the hypothalamus produces corticotropin-releasing hormone (CRH). This process is part of the hypothalamic-pituitary-adrenal (HPA) axis, which plays a crucial role in the body's response to stress. ACTH then stimulates the adrenal glands to produce cortisol, a vital hormone involved in various bodily functions, including metabolism and the immune response.

The other options refer to hormones that are regulated or released through different mechanisms or pathways. Insulin is produced by the pancreas and is involved in glucose metabolism. Cortisol, while it is a product of adrenal gland activity stimulated by ACTH, is not directly released from the pituitary. Adrenaline, or epinephrine, is produced by the adrenal medulla and is primarily involved in the fight-or-flight response, independent of direct hypothalamic stimulation via the pituitary gland.

Thus, ACTH is specifically linked to the release of hormones from the adrenal glands as a direct response to hypothalamic signals, making it the correct choice in this context.