It is a scientific law
Step-by-step explanation:
A scientific law states a constant relationship between two or more variables, each of which represents a property or measurement of specific systems. It is a constant and unchanging rule, usually expressed mathematically which allows to predict the unknown based on what is known with logical and real relationships.
A scientific theory is a set of concepts and rules (scientific laws) that express the relationships between observations of such concepts and generates a principle or set of principles to explain a phenomenon.