Which one of the following statements about energy is correct ?

The statement that energy can neither be created nor destroyed is a fundamental principle of physics known as the Law of Conservation of Energy. This principle is formally defined as the First Law of Thermodynamics [1]. According to this law, the total energy of an isolated system remains constant over time; it can only be transformed from one form to another, such as solar energy converting into chemical energy or heat [1]. In any system of constant mass, while energy may be transferred between a system and its surroundings through heat or work, the total energy of the universe is conserved. This means that while energy can change its state—for instance, from potential to kinetic or from light to heat—the absolute quantity of energy in a closed system never increases or decreases.

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > 1.14 Environment and Ecology > p. 14