Which of the following are opening/closing remarks?

• Группы
  • Opening remarks
  • Closing remarks
• Варианты
  • Hope you are OK.
  • Sorry, I didn't write earier but I was busy with schoolwork.
  • How is it going?
  • Sorry, it took me so long to write, I was busy at school.
  • That's all for now.
  • I have to go now.
  • Write back soon.
  • Sorry, I have to finish now.