**Core Concept**
Congenital Adrenal Hyperplasia (CAH) is a group of inherited disorders characterized by the deficiency of enzymes involved in the biosynthesis of cortisol and aldosterone. This results in an imbalance of glucocorticoids and mineralocorticoids, leading to various clinical manifestations.

**Why the Correct Answer is Right**
The correct answer is related to the enzyme 17,20-desmolase, which is involved in the conversion of 17-hydroxyprogesterone to androstenedione. A deficiency of this enzyme leads to an accumulation of 17-hydroxyprogesterone, which is then shunted towards the production of androgens, resulting in an excess of androgens. However, the deficiency of 17,20-desmolase leads to a decrease in the production of cortisol and aldosterone, resulting in a mineralocorticoid deficiency.

**Why Each Wrong Option is Incorrect**
**Option A:** 11-beta hydroxylase deficiency is a common variant of CAH, but it is characterized by an excess of mineralocorticoids due to the accumulation of 11-deoxycortisol, which has mineralocorticoid activity.

**Option B:** 3-beta hydroxylase deficiency is a rare variant of CAH, but it is not typically associated with mineralocorticoid deficiency.

**Option C:** 21-hydroxylase deficiency is the most common variant of CAH, and it is characterized by a deficiency of both cortisol and aldosterone, resulting in a glucocorticoid and mineralocorticoid deficiency.

**Clinical Pearl / High-Yield Fact**
A key feature of 17,20-desmolase deficiency is the presence of salt-wasting and hypokalemia, despite the presence of hypertension due to the excess of deoxycorticosterone, a potent mineralocorticoid.

**Correct Answer:** C.