**Core Concept**
Cushing's syndrome is a clinical condition caused by excess levels of cortisol in the body, resulting from various etiologies such as ACTH-producing pituitary adenomas, adrenal gland disorders, or exogenous steroid use. The clinical manifestations of Cushing's syndrome include weight gain, hypertension, glucose intolerance, and characteristic skin changes.

**Why the Correct Answer is Right**
The pathophysiology of Cushing's syndrome involves the overproduction of cortisol, which is mediated by the adrenocorticotropic hormone (ACTH) produced by the pituitary gland. ACTH stimulates the adrenal cortex to produce cortisol. The excess cortisol can lead to a variety of symptoms, including weight gain, hypertension, and glucose intolerance. The skin changes characteristic of Cushing's syndrome, such as striae and acne, are also due to the effects of excess cortisol.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because Cushing's syndrome can indeed be caused by a variety of factors, including ACTH-producing pituitary adenomas, adrenal gland disorders, and exogenous steroid use.
* **Option B:** This option is incorrect because one of the hallmark symptoms of Cushing's syndrome is indeed weight gain, particularly in the central part of the body.
* **Option C:** This option is incorrect because hypertension is a common finding in patients with Cushing's syndrome due to the effects of excess cortisol on the cardiovascular system.

**Clinical Pearl / High-Yield Fact**
One of the key distinguishing features of Cushing's syndrome is the presence of purple striae on the abdomen, which are due to the effects of excess cortisol on the skin.

**Correct Answer:** None of the above