Final answer:
A user story is a description of a feature from an end-user perspective, and the user story among the given options is 'As an authenticated user, I want to see all my action items.'
Step-by-step explanation:
A user story is a technique in software development used to capture a description of a feature, from the perspective of an end-user. It typically follows the format 'As a , I want so that '. Among the given options, the following is a user story:
a) As an authenticated user, I want to see all my action items.
The other options are not user stories as they do not follow the user story format or do not describe the desired feature from an end-user perspective.