The correct option is (d) Coke oven gas
Best explanation: Coke oven gas is a fuel gas having a medium calorific value that is produced during the manufacture of metallurgical coke by heating bituminous coal to temperatures of 900^oC to 1000^oC in a chamber from which air is excluded. The main constituents are 50% H2, 30% methane and 3% higher hydrocarbons, 7% CO, 3% CO2 and 7% N2. The gas has heating value of about 20,000 KJ/m^3.