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\ufeff5. \ufeffPBFT Answer the following questions about the Practical Byzantine Fault Tolerance protocol: (a) (3 \ufeffpoints) \ufeffHow does PBFT prevent faulty replicas from impersonating other non- \ufefffaulty replicas? (b) (4points)Consider a faulty primary that includes different client requests for sequence number i in pre-prepare messages it sends to backup replicas. How does PBFT ensure that non-faulty replicas do not execute different commands for log slot i? (c) (10 \ufeffpoints) \ufeffYou have implemented PBFT, \ufeffbut realized it is too slow. You therefore decided to remove the commit phase of the protocol (Figure 1 \ufeffof the PBFT paper). \ufeffIs your optimized version of the protocol correct? If yes, justify your answer. If no, \ufeffgive a sequence of events that leads to a safety violation.