A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic of choosing an instrument. It does not refer to any previous information. It sets the stage for the learner's journey in music. Why other lines are not chosen? Paragraph 2 starts with "Once an instrument has been selected," which needs context from the first sentence. Paragraph 3 starts with "As skills develop," which also needs prior information. Paragraph 4 starts with "Mastery of an instrument," which assumes knowledge of the topic.

Concluding sentence: Why this is the last line? This paragraph is the last because it summarizes the journey of learning an instrument. It shows the final goal of mastering the instrument.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects to Paragraph 1 because it follows the logical order of events. After choosing an instrument, the next step is to learn the basics.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 follows Paragraph 2 because it shows the logical order of learning. After learning the basics, learners develop skills to tackle more challenging pieces.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects to Paragraph 3 because it continues the logical order of learning. After developing skills, mastery comes next.