According to the law of conservation of energy:
(A) Energy exists in only one form
(B) Energy can be created but not destroyed and it can be transformed from one form to another
(C) Energy exists in many forms but it cannot be transformed
(D) Energy can neither be produced nor be destroyed and it can be transformed from one form to another

Hint:Here we have to discuss the law of conservation of energy and observe the options one by one to arrive at the conclusion. This law is derived from the first law of thermodynamics.

Complete step by step answer:
Energy conservation law specifies that energy can neither be generated nor wastes- it can only be transferred from one source of energy to another. This means that, whether it is applied from the outside, a system still has the same amount of energy.In the case of non-conservative forces, in which energy is converted from mechanical to thermal energy, this is especially complicated, but the total energy stays the same. The only way to use energy is to convert energy from one shape to another.Energy conservation plays a very significant role and it also affects our climate through the use of non-renewable resources. In particular, the use of fossil fuels for air and water emissions, such as carbon-dioxide, is generated by the burning of gasoline, coal and gas in power plants, heating systems and car engines.So, from the above discussion we can conclude that option D is the correct answer.

Note:The conservation of energy is not about minimising the usage of resources that would inevitably run out completely. Reducing demand for a finite resource and encouraging the resource to start restoring itself would be the perfect form of conservation. Sometimes, swapping the electricity consumed with an alternative is the only way to achieve this.
Therefore, in an independent system, such as the universe, if there is a lack of energy in any part of it, an equivalent amount of energy must be obtained in another portion of the universe. There is no known example of a violation of the energy conservation law till date.