On a request form, which Variable type should be used for indicating when the requester needs to receive the item?

The most appropriate choice in this scenario is the variable type that specifically denotes a point in time when the requester needs to receive the item, which is represented by the option "Due Date."

Using a "Due Date" variable allows you to capture the specific deadline by which the requester expects to receive the requested item. This is particularly important in IT Service Management (ITSM) because it helps in monitoring and managing service deliverables against client expectations. A due date can also support service level agreements (SLAs) and better prioritization of requests by setting clear timeframes.

In contrast, simply using a "Date" variable may not convey the urgency or context of needing the item by a certain date, thus lacking the specific indication of a deadline. A "Date Picker" provides a user-friendly interface for selecting a date, but again, it does not imply the urgency associated with it being a due date. "Duration" refers to a span of time rather than a specific point in time, which does not meet the requirement of indicating when the requester needs the item by.

In summary, "Due Date" is the most effective variable type for indicating a specific and urgent requirement date for receiving an item in a request form.