Final answer:
The best assistance a sales associate can offer to a customer looking for an out-of-stock item is suggesting an alternative product, and if possible, providing information on restock dates or offering notification services.
Step-by-step explanation:
When a customer is looking for an item that is out of stock, the best way a sales associate can assist is by offering an alternative product. This approach not only shows that the associate is eager to help but also maintains the customer's interest in the store's offerings. Another good practice is to inform the customer of when the item will be back in stock and offer to notify them or make a special order. Suggesting that they visit a different store is also a customer-friendly option, but it should be done after checking for alternative solutions within the same store to retain the customer.