A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic of hosting a gathering. It gives a broad overview of what is needed to start planning. It does not use any pronouns or definite articles that refer to previous ideas. Why other lines are not chosen? Paragraph 2 starts with 'Next,' which shows it is not independent. Paragraph 3 starts with 'On the day,' which also needs context. Paragraph 4 starts with 'Finally,' showing it is not independent either.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the ideas about hosting a gathering. It uses the word 'Finally,' which signals the end of the discussion. It also summarizes the importance of catering to guests' needs.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it follows the logical order of planning a gathering. After making a plan, the next step is to send out invitations.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects to Paragraph 2 because it follows the chronological order. After sending invitations, the next step is to prepare the space on the day of the event.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues the logical order of the event. After setting up the space, it is important to provide food and drinks for the guests.