Ravi collected four different types of fuels I, II, in, and IV. He wants to find out which fuel is the most efficient among the fuels he has collected. He bums 1.2 kg of I, 4 kg of II, 3.2 kg of III, and 2.4 kg of IV completely. He found out that the heat produced by complete burning of I, II, III, and IV is 7200 kJ, 32000 kJ, 12800 kJ, and 16800 kJ respectively. From this experiment, he concluded that _i_ is the most efficient fuel and its calorific value is _ii_. The information in which alternative completes the given statement?

• A.  i-I, ii-5000 kJ/ kg  
• B.  i-II, ii-8000 kJ/ kg
• C.  i-II, ii-6000 kJ/ kg 
• D.  i-IV, ii-8000 kJ/ kg