What is one of the purposes of the letterA．To cong

单项选择题

Ryan Miller,
General Manager,
Lexington Computer, Inc.
Date: May 15th
Dear Mr. Miller,
It is with immense pleasure to congratulate you on the successful completion of 20 years in the company. We are going to give you a party this evening in the office. We hope that you will attend our small party for you to make this moment memorable for us.
I know it is hard to achieve such a thing for anyone, but it is your hard work dedication and passion that enabled you to achieve such a milestone. I hope that you will continue to achieve such milestones in future as well. You have been an inspiration to us.
I once again congratulate you on your achievement.
Sincerely,
Richard Henderson
Assistant Manager

What is one of the purposes of the letter

A．To congratulate Mr. Henderson for retiring
B．To invite Mr. Miller to a celebration party
C．To notify employees of Mr. Miller"s promotion
D．To confirm Mr. Miller"s transfer request