Sitecore 9 Certification Practice Test

When a rendering parameter field doesn’t store the actual text you want, you’re dealing with a reference rather than a value. In Sitecore, many parameter types store the ID of another item (for example, a Droplink or Droptree). To obtain the real value, you must resolve that reference by retrieving the item using the stored ID and then read the value from that item’s fields (or its name) you need.

So you take the value stored in the parameter (the ID), fetch the referenced item from the content tree, and then access the field or property on that item to use in your rendering. If there are multiple IDs, resolve each one similarly.

This is why retrieving by its ID is the correct approach.