**Core Concept**
Forced alkaline diuresis is a treatment approach used to enhance the elimination of certain drugs and toxins from the body by increasing urinary pH, which increases the ionization of weakly acidic substances, thereby promoting their excretion in the urine. This method is particularly effective for eliminating acidic substances that are poorly soluble in water.

**Why the Correct Answer is Right**
The mechanism of forced alkaline diuresis involves administering a base, such as sodium bicarbonate, to increase the urinary pH. This increase in pH leads to the ionization of weakly acidic substances, making them more water-soluble and increasing their excretion in the urine. The correct answer is **Barbiturates**, as they are weakly acidic and can be effectively eliminated from the body through forced alkaline diuresis. This method is particularly useful in managing barbiturate poisoning, as it can help reduce the toxicity and improve the elimination of the drug.

**Why Each Wrong Option is Incorrect**
* **Option A:** **Phenobarbital** is a barbiturate, but the question seems incomplete, please provide the rest of the options.
* **Option B:** **Digoxin** is a cardiac glycoside that is eliminated primarily through the kidneys. However, its elimination is not significantly affected by forced alkaline diuresis.
* **Option C:** **Salicylates** (e.g., aspirin) are weakly acidic and can be eliminated through forced alkaline diuresis. However, this is not the most commonly used treatment approach for salicylate poisoning.
* **Option D:** **Tricyclic antidepressants** (TCAs) are weakly basic and are not effectively eliminated through forced alkaline diuresis.

**Clinical Pearl / High-Yield Fact**
Forced alkaline diuresis is most effective in eliminating weakly acidic substances, such as barbiturates, from the body. This treatment approach should be used under close medical supervision, as it can lead to complications such as metabolic alkalosis.

**Correct Answer: C. Barbiturates**