What are the steps of writing an apology letter？

What are the steps of writing an apology letter？
A.State the problem and give explanation for what happeneD.B.Arrange for a future action to make up.
C.Apologize again or give thanks for understanding.
D.Give your apology at the beginning of the letter.
正确答案：State the problem and give explanation for what happened.Arrange for a future action to make up.Apologize again or give thanks for understanding.Give your apology at the beginning of the letter.