Which of the following is the most commonly used chemical for ripening of fruits in India?

Calcium carbide is the chemical most commonly used, illegally, to ripen fruit such as mangoes in India: on contact with moisture it gives off acetylene, which mimics the natural ripening gas ethylene, and its use is banned under the food safety rules because of arsenic and phosphorus impurities. Silver iodide is used in cloud seeding, potassium iodide as an iodine supplement, and ammonium nitrate as a fertiliser and explosive.