This scenario describes a situation where a user has already successfully logged into the system (i.e., has been authenticated) but cannot access a particular network resource (the shared folder). This falls under the concept of authorization, which determines what actions or resources a user is permitted to access after authentication.

“Authorization is the process of granting or denying access to network resources once the user has been authenticated.” — CompTIA ITF+ Official Study Guide

Authentication verifies the identity of the user (e.g., username and password).

Authorization controls access rights (e.g., shared folders, files).

Accounting tracks user activity (e.g., audit logs).

Non-repudiation ensures actions or transactions cannot be denied later.

Therefore, the correct answer is B: Authorization.