CapDemo.GUI.ViewQuestion.btn_EditQuestion_Click C# (CSharp) Method

        private void btn_EditQuestion_Click(object sender, EventArgs e)
        {
            btn_EditQuestion.Visible = false;
            btn_Save.Visible = true;
            btn_addAnswer.Visible = true;
            flp_Answer.Controls.Clear();
            txt_ContentQuestion.ReadOnly = false;

            //GET QUESTION BY ID Question
            QuestionBL QuestionBL = new QuestionBL();
            List<DO.Question> QuestionList;
            Question question = new Question();
            QuestionList = QuestionBL.GetQuestion();
            if (QuestionList != null)
            {
                for (int i = 0; i < QuestionList.Count; i++)
                {
                    if (QuestionList.ElementAt(i).IDQuestion == IDQuestion)
                    {
                        txt_Catalogue.Text = QuestionList.ElementAt(i).NameCatalogue;
                        txt_ContentQuestion.Text = QuestionList.ElementAt(i).NameQuestion;
                        txt_QuestionType.Text = QuestionList.ElementAt(i).TypeQuestion;
                        txt_Date.Text = QuestionList.ElementAt(i).Date.ToString("d");
                    }
                }
                //GET ANSWER BY ID QUESTION
                List<DO.Answer> AnswerList;
                Answer answer = new Answer();
                question.IDQuestion = IDQuestion;
                AnswerList = QuestionBL.GetAnswerByQuestionID(question);
                if (AnswerList != null)
                {
                    for (int j = 0; j < AnswerList.Count; j++)
                    {
                        Answer_OnlyOneSelect OneChoiceAnswer = new Answer_OnlyOneSelect();
                        i++;
                        OneChoiceAnswer.Tag = i;
                        OneChoiceAnswer.ID_Answer = i;
                        OneChoiceAnswer.onDelete += OneChoiceAnswer_onDelete;
                        OneChoiceAnswer.onCheck += OneChoiceAnswer_onCheck;
                        OneChoiceAnswer.rad_check.Text = Convert.ToChar(a+j).ToString();

                        OneChoiceAnswer.txt_Answercontent.Text = AnswerList.ElementAt(j).ContentAnswer;
                        OneChoiceAnswer.rad_check.Checked = AnswerList.ElementAt(j).IsCorrect;

                        flp_Answer.Controls.Add(OneChoiceAnswer);
                    }
                }
            }
        }