Quick action source list of Reason for Legal Employer change?

Summary

Quick action source list of Reason for Legal Employer change?

Content

Hello,

We would like to know what is the lookup for the field 'Reason for Legal Employer change' list.
The screen is the quick actions ->  'Change Legal Employer'
We would like to add a value to the list, but cant find it under the lookup of actions .

see screenshots .
Thanks
Revital