The correct choice is (b) Bituminous coal
Best explanation: Bituminous coal is the most commonly used form of coal. It is available in both caking and non-caking forms. It burns with a yellow flame. It has calorific value of about 32000 kJ/kg. It consists of 81%C; 5%H2; 8% O2; 1.5% N2; 1% S; and 3.5% ash. Caking bituminous coal softens and forms a pasty mass if heated at higher temperature. This coal is used to manufacture coke. Non-caking bituminous coal doesn’t soften on heating and hence it is used in steam power plants.