The correct option is A Methyl isocyanate (MIC)
The Bhopal gas tragedy, also referred to as the Bhopal disaster, was a gas leak incident on the night of 2–3 December 1984 at the Union Carbide India Limited pesticide plant in Bhopal, Madhya Pradesh, India. It is considered among the world's worst industrial disasters. Over 500,000 people were exposed to methyl isocyanate (MIC) gas. The highly toxic substance made its way into and around the small towns located near the plant. Estimates vary on the death toll. The official immediate death toll was 2,259.