**Core Concept**
Magaldrate is a magnesium-aluminium hydroxide antacid that acts as a buffer in the gastrointestinal tract. It is not directly active in its administered form but undergoes conversion in the acidic gastric environment to release active components.

**Why the Correct Answer is Right**
Magaldrate is a complex of magnesium hydroxide and aluminium hydroxide. When exposed to gastric acid (HCl), it undergoes acid-base reaction, where the hydroxides neutralize acid and convert into their respective salts. Magnesium hydroxide and aluminium hydroxide are the active components released, providing neutralizing effects and reducing gastric acidity. This dual-action makes it effective for treating acid reflux and peptic ulcers.

**Why Each Wrong Option is Incorrect**
Option A: Magnesium hydroxide alone is not the final product; aluminium hydroxide is also released.
Option B: Calcium carbonate is not present in magaldrate; it is found in other antacids like calcium carbonate.
Option D: Aluminium hydroxide is present, but calcium carbonate is not a component of magaldrate.

**Clinical Pearl / High-Yield Fact**
Magaldrate is a combination antacid with both magnesium and aluminium hydroxide, which provides sustained relief from acid-related symptoms. The aluminium component reduces gastrointestinal motility, while magnesium acts as a mild laxative — a key point in managing side effects.

✓ Correct Answer: C. Magnesium hydroxide and Aluminium hydroxide