A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It tells us who Alcmaeon is and his importance in biology. This is a broad overview of his contribution. It does not refer to any previous information, so it stands alone. Why other lines are not chosen? Paragraph 2 starts with "Crotona is famous" which refers to a specific place and does not stand alone. Paragraph 3 starts with "But in the course" which is a conjunction and needs more context. Paragraph 4 starts with "His aim is not anatomical" which uses a pronoun and needs prior context. Paragraph 5 starts with "But in the course" which is also a conjunction and needs more context.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the information about Alcmaeon's contributions. It shows the outcome of his work and ties back to his importance in biology.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): This pair connects because Paragraph 2 gives more information about Crotona, where Alcmaeon lived. It uses the connector "but" to show a contrast between Alcmaeon and the Pythagorean scholars.
• Pair 2 (Paragraph 2 → Paragraph 3): This pair connects because Paragraph 3 continues to talk about Alcmaeon. It shows what Alcmaeon did, linking his background in Crotona to his scientific work.
• Pair 3 (Paragraph 3 → Paragraph 4): This pair connects because Paragraph 4 explains Alcmaeon's aim. It shows that even though he practised dissection, his main interest was different.
• Pair 4 (Paragraph 4 → Paragraph 5): This pair connects because Paragraph 5 shows the result of Alcmaeon's research. It uses "but" to show that despite his aim, he still made important discoveries in anatomy.