Which chemical process is essential for separating ions in electrolysis?

The correct choice emphasizes the specific process of electrolysis itself, which is the method utilized to separate ions. In electrolysis, an electric current is passed through an electrolyte, which causes the decomposition of the substance. Positive ions move towards the negatively charged electrode (cathode) where they gain electrons (reduction), while negative ions migrate towards the positively charged electrode (anode) where they lose electrons (oxidation).

Electrolysis is distinct in its function as it is the overall process enabling the separation and migration of ions. Ionization refers to the formation of ions from a neutral atom or molecule, but it is not the process that directly separates the ions in the context of electrolysis. The concepts of oxidation and reduction are integral reactions occurring at the electrodes during electrolysis but do not encapsulate the entire process. Electrolysis is fundamental for achieving separation in this scenario.