Final answer:
In this situation, the preferred customer should be prioritized, and the sales associate can apologize to the waiting customer.
Step-by-step explanation:
In this situation, the sales associate should prioritize the preferred customer and handle their transaction first (Option A). The preferred customer is entitled to their gift as part of the mailed promotion, and it is important to fulfill that commitment. This can help maintain customer loyalty and satisfaction. The sales associate can apologize to the waiting customer and explain the situation (Option B) to help alleviate their anger.
Offering a similar promotional gift to the waiting customer (Option C) may not be feasible as it may disrupt the promotion or cause confusion among other customers. Asking the preferred customer to step aside temporarily and assist the waiting customer (Option D) can lead to dissatisfaction and create further delays for both customers.