Fuel ‘X’ has a calorific value of 50 kJ/g and produces carbon dioxide and water on combustion where as Fuel ‘Y’ has calorific value 35 kJ/g and produces oxides of sulphur and nitrogen on combustion. Which is a better fuel?

• A. Both fuels X and Y are equally bad
• B. Both fuels X and Y are equally good
• C. Fuel ‘X ‘is better than Fuel ‘Y’
• D. Fuel ‘Y’ is better than Fuel ‘X’