Which concept does the first law of thermodynamics confirm?

The first law of thermodynamics, also known as the law of energy conservation, confirms the concept of energy conservation. This fundamental principle states that energy within an isolated system remains constant, implying that energy cannot be created or destroyed but can only change forms. For example, during thermodynamic processes, energy can be transformed from heat to work or stored as internal energy within the system. The total energy input to a system, considering both heat and work, equals the change in the system’s internal energy. This law underpins the conservation of energy in all physical processes, providing a foundational framework for understanding energy transformations in various scientific and engineering contexts. It ensures that, regardless of the process, the total energy before and after remains the same. Thus, the first law of thermodynamics explicitly confirms the concept of energy conservation, making the correct answer [A] Energy conservation.