Order the following continual service improvement (CSI) implementation steps into the correct sequence in alignment with the plan, Do, Check, Act (PDCA) model.
(1) Allocate roles and responsibilities to work on CSI initiatives.
(2) Measure and review that the CSI plan is executed and its objectives are being achieved.
(3) Identify the scope, objectives and requirements for CSI.
(4) Decision on implementation of further enhancement.