Which hormone is classified as a glucocorticoid?

The hormone that is classified as a glucocorticoid is cortisol. Glucocorticoids are a class of steroid hormones that are produced in the adrenal cortex and are primarily involved in regulating metabolism, inflammation, and the body's stress response.

Cortisol plays a significant role in glucose metabolism by promoting gluconeogenesis, which is the production of glucose from non-carbohydrate sources, primarily in the liver. This hormone also helps maintain blood pressure, manage the immune response, and reduce inflammation, making it critical for stress management and overall metabolic function.

Other options in the question represent different classes of hormones: adrenaline, also known as epinephrine, is a catecholamine involved in the body's fight-or-flight response; aldosterone is a mineralocorticoid responsible for regulating sodium and water balance; and estrogen is a sex hormone involved in the regulation of the female reproductive system and secondary sexual characteristics. Thus, among the choices, cortisol specifically fits the classification of glucocorticoids due to its functions and origin.