Final answer:
The Microservices architecture is most suitable when an event needs to initiate multiple workflow processes due to its modular nature that allows for independent scaling and fault isolation.
Step-by-step explanation:
Optimal Architecture for Initiating Multiple Workflow Processes
When considering an architecture where one event needs to initiate multiple workflow processes, the most suitable architecture is often Microservices. This architectural style divides a system into a collection of services that are highly maintainable and testable, loosely coupled, independently deployable, and organized around business capabilities. In contrast to monolithic architecture, where all processes are tightly integrated into one large system, microservices allow for each process to run independently. This enables easier scaling and better fault isolation. Serverless architecture could also be a viable option, particularly when individual functions are triggered by specific events, although it is less focused on structuring the entire system into services like microservices. A distributed architecture generalizes the concept of multiple systems working together, which microservices are a subset of, but it doesn't specify the granularity of the distribution as clearly.