Which of the following describes the method used to express the composition of a substance through subscripts and chemical symbols?

The method used to express the composition of a substance through subscripts and chemical symbols is known as a formula. A chemical formula provides a way to convey important information about the quantities of different elements that make up a compound. For example, in the formula H₂O, the subscript '2' indicates that there are two hydrogen atoms for every one oxygen atom in water. This concise representation allows chemists to understand and communicate the molecular structure of substances clearly and efficiently.

Other concepts like an equation typically refer to a representation of a chemical reaction, where reactants are transformed into products, incorporating formulas but not specifically describing composition. A chemical reaction discusses how substances interact and change during a process. Symbolism might refer to using symbols to convey various meanings, but it is not a specific term widely used in chemistry to describe the representation of chemical compounds.