**Core Concept**
The Bhopal gas tragedy was a catastrophic industrial disaster that occurred on December 3, 1984, in Bhopal, India, due to a massive release of methyl isocyanate (MIC) gas from a Union Carbide pesticide plant. The incident highlighted the importance of proper safety protocols and emergency preparedness in industrial settings.

**Why the Correct Answer is Right**
The tragedy was caused by a combination of human error and design flaws in the plant's safety systems. On the night of the incident, a batch of MIC was being stored in a tank that was not designed to handle the pressure of the gas. As the temperature rose, the pressure inside the tank increased, leading to a rupture and the release of a massive amount of MIC gas into the atmosphere. The gas spread quickly through the nearby residential areas, causing widespread harm to the local population. **Option C: MIC gas leak** is the correct answer because it accurately identifies the primary cause of the tragedy.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the type of gas involved in the tragedy. While carbon dioxide is a common industrial gas, it was not the primary cause of the Bhopal disaster.

**Option B:** This option is incorrect because it does not accurately describe the sequence of events leading to the tragedy. While maintenance issues may have contributed to the incident, they were not the primary cause.

**Clinical Pearl / High-Yield Fact**
The Bhopal gas tragedy is a classic example of a preventable disaster caused by a combination of human error and design flaws. It highlights the importance of proper safety protocols, emergency preparedness, and public awareness in industrial settings.

**Correct Answer:** C. MIC gas leak