**Core Concept**
Garlicky odour in gastric contents is a classic clinical sign of **organophosphorus poisoning**, where **phosphorus** compounds metabolize to produce volatile sulfur compounds that mimic garlic smell. This is due to the release of phosphine gas (PH₃) during metabolic breakdown of phosphorus-containing substances.

**Why the Correct Answer is Right**
In **phosphorus poisoning**, especially from white phosphorus (e.g., in accidental ingestion or burns), the body releases **phosphine gas (PH₃)** during metabolism. PH₃ has a strong, distinctive **garlicky or rotten egg odour** and is exhaled or detected in gastric secretions. This is a hallmark sign of phosphorus toxicity, differentiating it from other elemental poisonings.

**Why Each Wrong Option is Incorrect**
Option A: Sulphur poisoning produces a **rotten egg smell**, not garlicky, and is due to hydrogen sulfide (H₂S), not phosphine.
Option C: Iodine poisoning causes **bitter, metallic taste** and is not associated with garlicky odour.
Option D: Chlorine poisoning leads to **pungent, bleach-like smell** and respiratory distress, not a garlicky odour.

**Clinical Pearl / High-Yield Fact**
Remember: **"Phosphorus = Garlicky smell"** — this is a key diagnostic clue in poisoning cases. Always consider phosphorus in any patient with a garlic-like odour from gastric contents.

✓ Correct Answer: B. Phosphorus