The flowchart below illustrates a wood cutting production line, including the processing times required at each station (e.g., 2 minutes needed to process a unit at Station A). Wood pieces enter this wood-cutting line and are processed at Station A on a first-come-first-served basis. Each station handles one unit at a time, and there is no unnecessary idle time. As soon as a station becomes available, it will begin processing a unit, provided there is one available. The unit is cut into two pieces, size S and size M, at Station A. Size S is then sent to Station B, and size M is sent to Station C for sanding and polishing. At Station D, every two pieces, one size S and one size M are inspected together for fitting and then assembled into a module unit. The process of inspecting and then assembling a module unit takes 3 minutes. Currently, there are thousands of units at Station A waiting to be processed. Andy indicates that each module unit takes 15 minutes (= 2+4+6+3) to make. We should be able to make 4 module units per hour. Bob believes we can make more per hour because he considers each module unit takes less than 15 minutes to make in this production line. On the contrary, Cindy believes that a wood piece might soon require over 15 minutes to move from Station A to the final destination, Station D, to be assembled into a module unit. She observes a growing queue forming within the production line and feels Andy's number is too optimistic. How many module units can be made per hour from this production line? You can follow the views from the above three managers to help your calculation. If none of them makes correct sense to you, provide your answer, calculation and explanation. Station A 2 min/unit Station B 4 min/unit Station C 6 min/unit Station D 3 min/unit module units/hour