Final answer:
The 1st law of thermodynamics states that energy cannot be created or destroyed, only transferred or transformed.
Step-by-step explanation:
The correct statement of the 1st law of thermodynamics is that energy cannot be created or destroyed; it can only be transferred or transformed. This principle is also known as the law of conservation of energy.
Contrary to options concerning entropy or spontaneous reactions, which relate to the second law of thermodynamics, the first law focuses solely on the conservation and transformation of energy within a system and between the system and its environment.