Final answer:
When a guest requests extra hot fudge for their sundae, the server should provide the additional portion and also be aware of the restaurant's policy on extra serving charges to inform the guest.
Step-by-step explanation:
If a guest requests an additional portion of hot fudge while eating a hot fudge sundae dessert, the server should: d. bring the additional portion and know the restaurant's policy regarding charges for additional servings. By doing so, the server can provide prompt service by bringing the additional portion to the guest, and they can also inform the guest about any additional charges, if necessary, according to the restaurant's policy. This prevents any surprise charges for the guest and ensures transparent and professional service.