Answer - B and C.
Always build components that are loosely coupled.
This is so that even if one component does fail, the entire system does not fail.
If you build with the assumption that everything will fail, you will ensure that the right measures are taken to build a highly available and fault-tolerant system.
Option D is incorrect because using multiple services increases cost and operational burden, rather use less and efficient services like serverless storage services and serverless compute services.
