Sure! Let's analyze the sentences for each question to find the correct arrangement.

**Question 16:**
- Sentence **c**: "Hi Emrah" – This is a greeting and should come first.
- Sentence **d**: "Yes, I’d love to come." – This is a response to an invitation.
- Sentence **a**: "It’s good to hear from you and many thanks for the invitation." – Acknowledges the written communication and expresses gratitude.
- Sentence **b**: "Please tell Mert I’d love to stay with him if he’s got a free room." – This follows the invitation and expresses a desire to stay.
- Sentence **e**: "See you soon." – This signals the end of the message.
- Sentence **f**: "Love, Mustafa" – This is the sign-off.

Thus, the correct arrangement is:
**c - d - a - b - e - f.**
So, the answer is **A. c - d - a - b - e - f.**

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**Question 17:**
- Sentence **b**: "Here’s how to encourage an imaginative act of kindness by making 'Messages in a Bottle'." – This introduces the concept.
- Sentence **a**: "Collect empty bottles (wash well!) and have family members write kind notes to friends and neighbors." – This is the first step in the process.
- Sentence **d**: "Stuff the bottles with the notes." – This follows after collecting the bottles and writing notes.
- Sentence **c**: "Then leave them anonymously on doorsteps or in mailboxes with a card that says 'Messages from a friend to brighten your day! Fill this bottle for another, then give it away!'" – This explains what to do after stuffing the bottles.

The correct arrangement is:
**b - a - d - c.**
So, the answer is **C. b - a - d - c.**

I hope this helps you! Good luck!