You are tasked with designing a highly available e$-$commerce platform for a large online retailer. The platform must handle millions of concurrent users, process a high volume of transactions, and maintain a consistent product catalog across geographically distributed data centers. Requirements: $$ High Availability: The platform must be operational $24/7$ with minimal downtime in case of failures. $$ Scalability: The system needs to handle increasing user traffic and transaction volume efficiently. $$ Data Consistency: Ensure all users see the same product information regardless of which data center they connect to$.$ Fault Tolerance: The system must be able to recover from hardware and software failures without significant data loss. a$).$ Discuss two different distributed system architectures $($e$.$g$.,$ Client$-$Server, Peer$-$to$-$Peer$)$ that could be used for this e$-$commerce platform. Explain the advantages and disadvantages of each architecture in the context of the given requirements. $(8$ marks$)$ b$).$ Focusing on the chosen architecture, propose specific techniques for achieving high availability, scalability, data consistency, and fault tolerance. Explain how these techniques address the individual requirements. $(8$ marks$)$ c$).$ Discuss potential challenges in implementing a distributed e$-$commerce platform. Identify one specific challenge and propose a solution to address it$.(4$ marks$)$