● Compressed Natural Gas (CNG): It has a high auto-ignition temperature (540 °C) , and a narrow range (5–15 percent) of flammability . So, it is less likely to ignite on hotsurfaces . So, option 1 is correct. ● It has a higher calorific value than diesel and petrol . So, option 2 is NOT correct. ● CNG mixes well with air and disperses quickly clearing the area of the fire. So, option 3 is correct.