Inserting Field Name of Object in Related Collection

As shown in the figure below, if you select the Activities collection and then select the Activity Status field from the object in that collection, only the API name ActivityStatus_c of the selected field is inserted.

A complete expression can't be inserted in this case because you can't use "dot" notation to work with a specific row in a collection to access its field value. You need to use Groovy code to access the collection of rows and then work with one row at a time.