Final answer:
The best option is to inform the customer about alternative burger options available at your store.
Step-by-step explanation:
The best option for you to respond would be to inform the customer that your store does not sell Big Macs, but you have other burger options available.
You can explain to the customer that although you don't have the specific Big Mac, you have similar options like the SuperBurger Special or the Deluxe Burger that they might enjoy.
You can also offer to customize a burger according to the customer's preferences by adding or removing ingredients.
This way, you provide an alternative solution to satisfy the customer's cravings while promoting your store's offerings.
It's important to remain courteous and helpful throughout the interaction to ensure good customer service and potentially gain a loyal customer.