Which of the following is the most appropriate diagram representing the flow of business operations after concurrent engineering is applied? Here, the arrows in the diagram show the flow of business operations, and each activity name is displayed on top. a) All four stages (Specifications → Production diagram → Process diagram → Production) proceed strictly sequentially, one finishing before the next starts. b) Specifications and Production diagram proceed sequentially; Process diagram and Production start with partial overlap of the previous stage. c) All stages run within one large feedback loop, with Production feeding back to Specifications. d) Each stage starts before the previous one finishes — Specifications starts first, then Production diagram begins while Specifications continues, then Process diagram begins while Production diagram continues, then Production begins while Process diagram continues (staggered overlapping start).