The study of the composition of substances is known as:

Explanation: Chemistry is a branch of science that deals with matters with its composition, structure, properties as well as its behaviour towards other matter. It therefore looks at how various entities behave and the transformations that occur when they are in a chemical process. Other Options: (A) Physics: Less concerned with the makeup of substances but will pay attention to the characteristics of matter and energy. (B) Mechanics: The branch of physics that helps in understanding the movement of an object in relation to space. (D) Biology: Living matter not the mixture of chemical reagents or the physical compound Substance.