**Core Concept**
Forced alkaline diuresis is a medical treatment used to enhance the elimination of certain toxic substances from the body by increasing urine production and altering the pH of the urine. This technique is particularly useful in cases of poisoning by weak acids, which are more soluble and excreted more efficiently in an alkaline environment.

**Why the Correct Answer is Right**
The underlying principle of forced alkaline diuresis involves administering a large volume of fluid and an alkaline substance, such as sodium bicarbonate, to increase urine production and reduce the pH of the urine. This facilitates the excretion of weak acid toxins, such as barbiturates, salicylates, and certain heavy metals, which are more soluble and easily excreted in an alkaline environment. The kidneys play a crucial role in this process, with the renal tubules actively secreting the alkaline substance and increasing the pH of the urine.

**Why Each Wrong Option is Incorrect**
**Option A:** Forced alkaline diuresis is not typically used in the treatment of poisoning by strong acids, such as hydrochloric acid or sulfuric acid, which are more readily excreted in their acidic form.
**Option B:** While forced alkaline diuresis may be used in some cases of poisoning, it is not the primary treatment for poisoning by weak bases, such as ammonia or cocaine, which require different therapeutic approaches.

**Clinical Pearl / High-Yield Fact**
Forced alkaline diuresis is most effective when used in conjunction with other treatments, such as activated charcoal and supportive care, to manage the acute symptoms of poisoning and enhance the elimination of toxic substances.

**Correct Answer: C. Barbiturates**