A good fuel is one which possesses:
(a) high calorific value and low ignition temperature
(b) high calorific value and high ignition temperature
(c) high calorific value and moderate ignition temperature
(d) low calorific value and moderate ignition tempeature
It should possess high calorific value so that the energy released on heating a specific amount of fuel is more. It should have a moderate ignition temperature, i.e., neither too high nor too low. Hence, the correct choice is (c).