单项选择题

December 22, 2004
Dear Ms. Lin,
By the end of 1997, I began to be an office worker in this company. Working as your assistant for the past five years has been genuinely rewarding experience. Under your direction I have grown as an administrator (管理人员). And I am grateful that you have given me a practical education in business administration.
As you may know, I have always been eager to broaden my knowledge in business administration and have additional experience in this field. Now I have such an opportunity and thus, I submit my resignation (递交辞呈) from the position of your assistant, effective from the 31th this month; but I could stay a week or two longer if needed to help train my replacement.
I leave with only good memories of you and the other people with whom I worked. Thanks to all of you for a valuable help to my career.
Yours sincerely,
Vince Agsaway
Vince found his past 5 years’ experience ______.

A) practical

C) grateful
B) genuine

D) rewarding