Which of the Following Is the Most Effective Closing Sentence

Multiple Choice

Which of the following is the most effective closing sentence for a bad-news message?

A) The service department can provide information gathered from customer feedback.
B) Once again, I'm sorry we can't afford to implement your suggested customer research project.
C) If you encounter additional problems, please let me know.
D) Feel free to call on me if I can be of further assistance to your department.
E) Although your proposed research would be beneficial, company policy forbids budget increases.