The transfer of ownership of government business to individuals is

Privatization is the transfer of ownership and control of a business from the government to private individuals or companies. Governments privatize enterprises such as airlines, telecommunications firms, or refineries when they want to reduce public spending, improve efficiency, or raise revenue by selling shares or assets to private investors.

The other terms describe related but different processes. Commercialisation means running a government-owned business on profit-making, commercial lines while ownership stays with the government. Deregulation means removing government rules and restrictions that control how a market or industry operates, without necessarily transferring ownership. Nationalization is the opposite of the process described in the question: it is when the government takes over ownership of a privately owned business.

Examination reminder: the key word that separates these terms is who ends up owning the business. If ownership moves from government to private hands, the answer is privatization; if it moves the other way, it is nationalization.