Which action would immediately halt all flow processes?

The action that would immediately halt all flow processes is "Terminate." This action is designed to completely stop a flow, ensuring that no further steps or actions will be executed. When a flow is terminated, it effectively ceases all functionalities related to that particular flow instance, preventing any subsequent actions that would normally follow.

In contrast, other options like "Stop" and "Pause" do not have the same impact. The "Stop" action may be interpreted as halting the flow temporarily, but not necessarily in a way that ensures all processes are completely terminated. "Pause" similarly suggests a temporary halt, allowing for the possibility of resuming the flow later. The term "End" could imply concluding the flow but does not clearly define the abrupt cessation of all active processes in the same definitive manner that "Terminate" does. Therefore, "Terminate" is the most appropriate choice for completely halting all flow processes.