I can think of a lot of cloud systems that have C. Businesses will rely on a single machine running a big Oracle DB. Microservice architectures will be eventual

I can think of a lot of cloud systems that have C. Businesses will rely on a single machine running a big Oracle DB. Microservice architectures will be eventually consistent as a whole, but individual services will again have a single DB on a single machine. The single machine is a beastly distributed system in of itself, with multiple cores, CPUs, NUMA nodes, tiered caches, RAM, and disks. But when it comes down to two writers fighting over a row, it's going to consult some particular physical place in hardware for the lock.