The appropriate reply to the question asked will be A. Amazing! I couldn't believe how much it has changed!
It should be noted that in this situation, a question is asked and an appropriate answer is required. Therefore, one can't say thank you for asking me.
Therefore, the appropriate answer to the question "How was your trip to Vietnam after 10 years?* will be "Amazing! I couldn't believe how much it has changed!
Learn more about questions on:
https://brainly.com/question/24373788