双击一个名为btnCom的按钮，自动生成的鼠标点击事件处理方法为： A: private void btnCom_Click(object sender, EventArgs e){ } B: public void btnCom_Click(object sender, EventArgs e){ } C: private void btnCom(object sender, EventArgs e){ } D: public void btnCom(object sender, EventArgs e){ }