Consider the following system. Note that operations P1 and P2 can occur simultaneously with, and independent of, operation P3. However, all three operations must be completed before operation P4 can start. Also notice that operation P5 has two independent and identical machines. If you want to improve the capacity of this system, which operation should you improve? (Hint. Note that the information provided is in terms of 'production rates', NOT 'process times')