Which property of the Parallel activity in UiPath allows you to specify a Visual Basic expression evaluated after each branch completes?

The property of the Parallel activity in UiPath that allows you to specify a Visual Basic expression evaluated after each branch completes is IdleTimeout. This property determines the time span after which, if no activities are being executed in the branches of the Parallel activity, the workflow will evaluate the provided expression. This allows for conditional operations or logging based on the completion of the individual branches within the Parallel activity.

When using Parallel activities, it's crucial to manage the execution flow effectively, especially when multiple tasks are executed concurrently. The IdleTimeout property enables developers to implement specific behaviors or handle transitions based on whether all tasks have completed or if any specific conditions are met within those branches. This provides flexibility and control over parallel execution in workflows.

The other options pertain to different functionalities. For instance, the Assign activity is used for assigning values to variables, Branches are the individual paths within a Parallel activity, and ChildActivities refer to the actual activities that can be included in the branches. None of these properties provide the functionality related to evaluating an expression after branches complete like IdleTimeout does.