Final answer:
Custom activities which can be added into a workflow include CodeActivity for executing procedural code, NativeActivity for more runtime control, and AsyncCodeActivity for non-blocking asynchronous operations.
Step-by-step explanation:
The types of custom activities that can be added into a workflow are B. CodeActivity, D. NativeActivity, and A. AsyncCodeActivity. CodeActivity is the simplest type of activity, which allows users to execute procedural code. NativeActivity provides more control over the workflow runtime and can schedule other activities, wait for events, and manage transactions. AsyncCodeActivity is used for asynchronous code execution, which doesn't block the workflow while waiting for an external event or long-running operation to complete. CorrelateCodeActivity is not a standard activity type, so it does not apply in this context.