Which of the Following Is the Best Buffer to Open

Which of the following is the best buffer to open a letter that refuses a request from a local nonprofit organization for a charitable donation?

A) This is to inform you that your kind letter of May 14 has been directed to me for reply.
B) We have received your letter requesting a donation to your annual fund-raiser.
C) The services you provide for homeless families in our community are necessary and important.
D) Although we admire what your organization does for our community, unfortunately, we are unable to donate to your fundraiser at this time.