Final answer:
The best approach in this situation is to excuse yourself, answer the phone, and assist the caller if they need a quick answer, and get back to your customer.
Step-by-step explanation:
When faced with the situation of answering a phone call while completing a sale with a customer, the best approach would be option D: Excuse yourself, answer the phone, and assist the caller if they need a quick answer, and get back to your customer.
This option allows you to prioritize both the customer at the store and the caller on the phone. By excusing yourself, you show respect and professionalism to both parties.
It is important to address the customer's needs first, as they are physically present in the store and may require your immediate assistance. However, it is also important to answer the phone in a timely manner, acknowledging the importance of prompt responses to customers on all platforms. If the caller requires a quick answer, you can provide assistance but should aim to return to your customer as soon as possible to ensure their needs are fully met.