D Question $41$ pts A bread$-$making factory has the production process shown in the figure below. There are five operations in sequence. The product only needs to go through one of the parallel machines in each case where parallel machines exist. What is the bottleneck operation of this process? Proof $60$ min.$/$batch Mix Bake Pack $50$ min$/$batch $60$ min.$/$batch $40$ min.$/$batch Proof Cut $60$ min.$/$batch $35$ min.$/$batch Mix Bake Pack $50$ min$/$batch Proof $60$ min.$/$batch $40$ min.$/$batch $60$ min.$/$batch O Mix O Proof O Bake O Cut O Pack