Solution:Concept- Kilojoule per kilogramme is the unit used to quantify a fuel's calorific value in calories. The quantity of energy released or created when 1 kg of fuel or any other substance burns in the presence of oxygen and the combustion products are cooled to STP is known as the calorific value.
Calorific value reflects the amount of heat produced by a unit of fuel. It aids in our ability to distinguish between excellent fuel and poor fuel.
Calorific value is used to estimate the fuel efficiency and is expressed as kilojoules per kilogram.
Hence, the correct answer is option (4).