Suppose You are working as a software architect for an online payment processing platform that handles millions of transactions per day. The platform is built using a microservices architecture, with key services such as payment gateways, fraud detection, and notification services interacting with each other. Recently, your team has experienced intermittent network issues and occasional service outages, leading to failed transactions and poor user experience.

a$)$ Propose a retry strategy that can handle transient failures $($e$.$g$.,$ network timeouts$)$ without overwhelming the dependent services

b$)$ Describe a fallback strategy for the fraud detection service that allows transactions to proceed when the service is down while maintaining security and compliance $[4$ Marks$]$