**Core Concept**
Addison's disease is a rare endocrine disorder characterized by the bilateral destruction of the adrenal cortex, leading to a deficiency in cortisol and aldosterone production. This results in various clinical manifestations due to the lack of these essential hormones.

**Why the Correct Answer is Right**
The clinical features of Addison's disease include fatigue, weight loss, hyperpigmentation, hypotension, and electrolyte imbalances. One of the key features is hyperkalemia due to the lack of aldosterone, which regulates potassium levels in the body. Additionally, patients may experience nausea, vomiting, and abdominal pain.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is a common feature of Addison's disease, as the lack of cortisol leads to increased ACTH levels, causing hyperpigmentation of the skin.
**Option B:** Weight loss is a classic symptom of Addison's disease, as the lack of cortisol impairs glucose metabolism and leads to muscle wasting.
**Option C:** Hypotension is a hallmark of Addison's disease, as the lack of aldosterone impairs the renin-angiotensin-aldosterone system, leading to decreased blood pressure.

**Clinical Pearl / High-Yield Fact**
A key clinical feature to remember is that patients with Addison's disease often have hyperkalemia, which can be life-threatening if not recognized and treated promptly.

**Correct Answer: D**