Consider the following statements regarding maintenance of machineries : 1. Corrective maintenance actions are maintenance activities that are carried out after a failure has occurred. 2. Corrective maintenance must be initiated immediately to restore critical systems to their functional state or can be deferred to a more convenient timing if the failure is not critical and does not need immediate action. 3. Preventive maintenance must be initiated immediately to restore critical systems to their functional state or can be deferred to a more convenient timing if the failure is not critical and does not need immediate action. Which of the above statements is/are correct ?