Which of the following is NOT a fossil source of energy?

Correct option is A

Out of the given options, only cow dung cakes are not a fossil source of energy. These are made from dried animal waste, primarily dung from cows. This biomass is a renewable energy source as it comes from organic matter that can be replenished.
Coal, kerosene oil, and CNG: These are all derived from fossil fuels. Coal is directly a fossil fuel, while kerosene oil is a refined product of petroleum (another fossil fuel), and CNG (Compressed Natural Gas) is mainly composed of methane, which is also a major component of natural gas (a fossil fuel).