Which of the Following Would Be the Most Effective Statement

Which of the following would be the most effective statement in a letter to a local charitable organization refusing its request for a donation?

A) Even though our budget won't allow a contribution this year, we hope to be able to contribute next year.
B) Please accept our sincerest apologies for being unable to donate to your cause.
C) We are unable to contribute this year because of budget constraints.
D) Unfortunately, company policy prevents us from donating to your cause.