Answer: C. b-a-c-d-e-f-g-h-i

This is the correct order for a formal letter:

1. Salutation: Dear Students,
2. Introduction: We are excited to invite you...
3. Activity 1: Ride a jeep...
4. Activity 2: Explore the seabed...
5. Activity 3: Take photos...
6. Activity 4: See a gong show...
7. Conclusion: We hope you can join us...
8. Closing: Best regards,
9. Signature: D-Class Teacher

Answer: B. a-g-h-c-e-d-b-i

This is the correct order for a friendly letter:

1. Salutation: Dear Nick,
2. Introduction: I hope you are well...
3. Body paragraph 1: It’s been a long time since...
4. Body paragraph 2: First, do you remember our trip to Da Lat?...
5. Body paragraph 3: And then, we had so much fun in Nha Trang...
6. Closing: Finally, I hope we can have more adventures soon...
7. Closing phrase: Take care,
8. Signature: Quan