Final answer:
The best response would be to apologize for the delay and assure the customers that their table will be ready soon. Offering complimentary drinks or a discount on the meal can be considered as gestures of goodwill.
Step-by-step explanation:
I would respond to the upset customers by option D) Assure them their table will be ready soon.
First, I would apologize for the delay and reassure them that their table will be ready in a few minutes. It's important to acknowledge their frustration and express empathy for their situation.
Offering complimentary drinks while they wait (option C) or explaining the situation and offering a discount on the meal (option B) could also be considered as gestures of goodwill to help alleviate their frustration.