**Core Concept**
The zona glomerulosa is the outermost layer of the adrenal cortex, responsible for producing and secreting a specific type of steroid hormone. This hormone plays a crucial role in maintaining electrolyte balance and blood pressure.

**Why the Correct Answer is Right**
The zona glomerulosa secretes aldosterone, a mineralocorticoid hormone that acts on the collecting ducts of the kidneys to regulate sodium and potassium levels in the blood. Aldosterone stimulates the reabsorption of sodium and the secretion of potassium, which helps to maintain the body's fluid balance and blood pressure. This process is mediated by the renin-angiotensin-aldosterone system (RAAS), which is activated in response to decreased blood volume or pressure.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the zona glomerulosa does not produce cortisol, which is primarily produced by the zona fasciculata. Cortisol has a wide range of effects on metabolism, immune function, and other processes, but it is not the primary hormone secreted by the zona glomerulosa.
**Option B:** This option is incorrect because the zona fasciculata produces androgens, such as dehydroepiandrosterone (DHEA), which are converted to estrogens and androgens in peripheral tissues. While the zona fasciculata does produce some aldosterone, it is not the primary source of this hormone.
**Option C:** This option is incorrect because the medulla of the adrenal gland produces catecholamines, such as epinephrine and norepinephrine, which are involved in the "fight or flight" response. These hormones are not produced by the zona glomerulosa.

**Clinical Pearl / High-Yield Fact**
Aldosterone escape is a phenomenon where the kidneys adapt to chronic aldosterone excess by increasing their sodium reabsorption, leading to hypertension. This highlights the importance of maintaining electrolyte balance and monitoring aldosterone levels in patients with hypertension or kidney disease.

**Correct Answer:** D. Aldosterone