**Core Concept**
In severe burn injuries, the body's response to trauma and inflammation leads to a complex interplay of electrolyte imbalances. The loss of skin integrity and subsequent fluid shift from the intravascular space to the interstitial space result in a significant shift of sodium, potassium, and other electrolytes.

**Why the Correct Answer is Right**
Severe burns lead to a massive release of stress hormones, including aldosterone. Aldosterone promotes the retention of sodium and water in the kidney, resulting in a dilutional hyponatremia (hypotonicity). Additionally, the release of antidiuretic hormone (ADH) from the posterior pituitary gland further contributes to water retention. As a result, the sodium level decreases, leading to a dilutional hyponatremia. This is known as the "central hypovolemic" hyponatremia. The body tries to compensate for the fluid loss by retaining sodium and water, but this results in hyponatremia.

**Why Each Wrong Option is Incorrect**
**Option A:** Although hyperkalemia can occur in burn patients due to tissue damage and rhabdomyolysis, it is not the most common electrolyte abnormality in this scenario.
**Option B:** Hypernatremia can occur in patients with severe burns, but it is typically seen in patients with inadequate fluid replacement or those with a history of diabetes insipidus.
**Option C:** Hypocalcemia can occur in burn patients due to the release of calcium from damaged tissues and the binding of calcium to albumin, which is often decreased in burn patients. However, it is not the most common electrolyte abnormality.

**Clinical Pearl / High-Yield Fact**
In severe burn patients, the initial fluid resuscitation should aim to replace the lost intravascular volume and maintain a sodium level between 135-145 mmol/L to prevent dilutional hyponatremia.

**Correct Answer:** C.