【单选题】

A

To Miss Doughty
16 September 1962, Sunday
My dear,
Well, here we are-but not here. You are in Princeton,and me in Quogue,and another brand new year is about to start for you. For me, too.
It is the beginning of a big year for you, in many respects your biggest so far. By the time, June comes around, you will be 18, and graduating from school. In the past week or so I have called you"Kid", but subconsciously I have been doing that because your kid days are over, or just about. I suspect that you are going through the experience of first love, and no matter what else happens, after that experience you are never a kid again.
Most of the nice things we associate with being a kid are okay while you are still a kid. But you gain more than you lose. You gain in understanding standing, in appreciation of people, in un-derstanding and appreciation of people. You begin to see the wisdom in that quotation I have so often repeated to you: to thine own self be true. Every year at this time I have repeated that quotation to you, and the time is not really too far distant when you will be passing it on to your own children. It is probably the best single piece of advice I can give you, or you can give them.
You have done well, and I am pleased with you, not only for what you have done, but for what you are. So good luck in your Senior Year, and always know that the old man loves you very much.
  After finishing the passage, we know__________.
A. it is a public letter to students
B. it is a poster from students' union
C. it is a letter from a father to a daughter
D. it is a dairy about growing up