Should keyboard users be able to tab outside an expanded menu.?

Question

1. a keyboard user presses enter on a navigation button to open the associated menu
2. the menu opens up
3. the user presses tab to navigate into the expanded menu
4. the user tabs through the expanded menu items
5. the user reaches the last item in the expanded menu

If the user now presses tab, should:

A) nothing happens, the user must close the menu or shift+tab back. It acts like a modal, the user is contained in the menu until they close it B) they are taken outside of the menu, to the next item in the tsb order. The menu doesn't close. C) as per 'b' but the menu automatically closes

Answer 1

It appears that option C is suggested here https://www.w3.org/WAI/ARIA/apg/patterns/disclosure/examples/disclosure-navigation/