Answer:
Option C, Chemical reaction
Step-by-step explanation:
In a chemical reaction, either two or more chemical substances combine to produce a new chemical compound or a large chemical molecule breaks down to produce smaller units.
In both the cases, the molecular structure of the reactant is reoriented to produce a new substance.
For example –
Fe(s) + S(s) → FeS(s)
Iron combines with sulfur to produce iron sulfide. In this reaction, the atoms with in the two elements i.e iron and sulfur, re-oriented and combined to form chemical bonds and hence produces a compound.
Hence, option C is correct