You validate the design for the complexity of the proposed automation solutions. The complexity can be a potential risk for the solution development and maintenance. 
Please select the automation solutions that have high complexity.

Answer options:

A.Business rules
B.Power Automate
C.PlugIns
D.Classic Workflows
E.Custom workflow actions

Correct Answers: C and E
Power Platform provides a variety of tools to extend the platform and user experience. If you need to work with the Dataverse, you can use the Dataverse Web API and Organization service. Or develop your business logic by using the Dataverse plug-ins. You can use Data import, Synchronization, Virtual entities, Azure integration, and Webhooks for integration purposes. 
The Dataverse server-side extensibility and automation options include compelling tools, like The business rules
The business process flows
Classic workflows
Plug-ins
Power Automate
All these components facilitate the Dataverse data operations. But they are different by the complexity that can be a risk factor for your solution. 
The business rule is the simplest out of the list of automation solutions. The rules work on the client and server sides. 
Classic Workflows have a medium complexity because it can run synchronously (Real-time) or asynchronously (Background). Workflows run only on the server-side. The Power Automate flows should be used instead of asynchronous (Background) workflows. 
Power Automate also has medium complexity. It runs only on the server-side and asynchronously. 
PlugIns automation has high complexity. The PlugIns business logic should be coded in .Net. You can run PlugIns synchronously or asynchronously. The use of the custom code brings this automation type to a high level of complexity and increases the risk for your solution. You need to use the PlugIns in your design only if you cannot achieve the business objectives by any other Power Platform products or components. 
The Custom workflow actions have high complexity as well because they can run a custom .Net code. You can trigger actions by Classic workflows. Contrary to PlugIns, the Custom workflow actions can execute no code actions as well. 
For more information about the use of the Dataverse automation and extensibility, please visit the below URLs: 

https://docs.microsoft.com/en-us/learn/modules/power-platform-architecture/5-logic
https://docs.microsoft.com/en-us/learn/modules/power-automate-architecture/1-introduction
https://docs.microsoft.com/en-us/powerapps/maker/data-platform/work-with-any-type-app
https://docs.microsoft.com/en-us/learn/modules/define-create-business-rules/1-rules
https://docs.microsoft.com/en-us/powerapps/developer/data-platform/apply-business-logic-with-code