Substance(s) written on the left-hand side of the chemical equation are known as
Reactant (s)
The explanation for the correct option:
(A) Chemical reactions: A chemical reaction is in which the bonds are broken within reactant molecules, and new bonds are formed within product molecules in order to form a new substance.
The explanation for the incorrect option:
(B) Product:
(C) Reaction:
Therefore, the correct option is option (A).