You Need to Convey to a Customer That His Shipment

You need to convey to a customer that his shipment will arrive a week late. Which of the following lines will be most effective in communicating this news?

A) We regret to inform you that your shipment will arrive a week late.
B) Due to unavoidable circumstances, your shipment has been delayed by a week.
C) Your shipment will be delivered next week.
D) Your shipment will arrive next week, even though we promised that you would receive it this week.