Demonetization refers to :

Option 1 -> This describes monetary policy control, not demonetization.

Option 2 -> This refers to controlling currency production, not removing existing currency from circulation.

Option 3 -> This suggests temporary removal, but demonetization is a permanent action.

Option 4 -> This correctly defines demonetization as the permanent withdrawal of legal tender status from specific currency denominations.

Hence, Option 4: Declaring all or few existing hard currency or coins as no longer a legal tender forever -> Demonetization is the act of stripping a currency unit of its status as legal tender permanently. When a government demonetizes currency, those specific notes or coins can no longer be used for transactions and must be exchanged or deposited within a specified period. For example, India's 2016 demonetization invalidated ₹500 and ₹1000 notes permanently, requiring citizens to exchange them for new currency -> correct