You have created a custom block “Festival Offer” and placed this block in the header...

Drupal 10 and Drupal 11 let you control block display through visibility conditions on the block configuration form. Drupal’s block management documentation explains that a block’s visibility can depend on page-specific visibility settings and also on user role conditions. For page visibility, Drupal specifically notes that the front page is an exception and must be entered as < front > . To show a block only on the homepage, you add < front > in the Pages visibility settings and choose “Show for the listed pages.”

To limit the block to a specific audience, you use the Roles visibility condition and select the exact role that should see the block. In this case, that is Premium customer , not the broader Authenticated user role, because selecting Authenticated user would show the block to all logged-in users who have that role, not just premium customers. Drupal core’s block form API also confirms that block visibility is built through configurable visibility conditions in the block UI.

So the correct combination is:

A for the role restriction, and B for the front-page-only restriction.