Our body can only extract energy from apple not from coal.Eating coal does not give us energy because our body cannot process and use coal for anything good. Moreover coal is toxic and it contains hydrocarbons within its structure that will make us sick if we consume it.Coal contains flammable hydrocarbons , therefore it gives energy on burning.On the other hand , apple has got nutrients which our body can process and get the required energy.
Our body has the capability to extract energy from apple and not from coal and it is a fact that coal is not eatable