To allow users to post comments on a Tableau visualization, two primary configurations are required. First, the commenting feature must be enabled at the site level within the Tableau Server or Tableau Cloud settings. This acts as a master switch for that specific site. Second, the relevant users or groups must be explicitly granted the "Add Comments" permission capability on the specific workbook or view. Without this permission, even if commenting is enabled for the site, users will not be able to add comments.

A. The relevant users must have a minimum site role of Explorer (can publish)

This is incorrect. Users with a "Viewer" site role can add comments, provided they have the specific "Add Comments" permission. An Explorer role is not the minimum requirement.

C. Comments must be enabled on the server Settings page

While a server-wide setting to enable comments does exist and must be active, the site-level setting is more specific and is the direct control for a particular site's functionality. The question implies configuration for a set of users, which is managed at the site and content level.

1. Tableau Server Help - Manage Site Settings (for option D):

In the "General" tab of the site settings, an administrator can configure commenting. The documentation states, "Allow users to comment on views. When you turn off comments, any existing comments are archived on the server." This confirms the site-level setting is required.

Source: Tableau Server Help, "Manage Site Settings," Section: "General tab settings."

2. Tableau Server Help - Permissions (for option B):

The official documentation on capabilities granted by permissions lists "Add Comments" as a distinct capability. It states, "To see and add comments, users need the View Comments and Add Comments permission capabilities." This confirms that the specific permission must be granted.

Source: Tableau Server Help, "Permissions," Section: "Capabilities granted by permissions."

3. Tableau Server Help - Set Users’ Site Roles (for option A):

The documentation outlines the capabilities for each site role. The "Viewer" role description includes the ability to "Add comments to views." This directly refutes the claim that Explorer (can publish) is the minimum required role.

Source: Tableau Server Help, "Set Users’ Site Roles," Section: "General capabilities for each site role."