## **Core Concept**
The question pertains to the characteristic pathological changes observed in the gastric mucosa following poisoning with specific substances. The description of a "red velvety appearance" is a key finding that needs to be linked to the correct toxic agent.

## **Why the Correct Answer is Right**
The correct answer, **C. Potassium permanganate**, is associated with a distinctive red or brown coloration of the gastric mucosa. When ingested, potassium permanganate causes severe mucosal damage, leading to a characteristic red, velvety appearance due to the oxidative effects of the permanganate ion. This results from the direct toxic effect of permanganate on the mucosal lining, causing necrosis and hemorrhage.

## **Why Each Wrong Option is Incorrect**
- **Option A:**
- **Alcohol** can cause gastric mucosal damage and may lead to erosions or ulcers, but it does not typically produce a red velvety appearance. Alcohol-induced changes are more often associated with superficial erosions.

- **Option B:**
- **Copper sulphate** poisoning can cause greenish discoloration of the gastric mucosa due to the deposition of copper salts, not a red velvety appearance.

- **Option D:**
- **Arsenic** poisoning may cause gastrointestinal symptoms and can lead to mucosal irritation, but it does not characteristically produce a red velvety appearance of the gastric mucosa.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the appearance of the gastric mucosa can be a critical clue in diagnosing the cause of poisoning. Potassium permanganate poisoning is specifically known for causing a red or purple discoloration of tissues, including a red velvety gastric mucosa.

## **Correct Answer:** . Potassium permanganate