A.I. Explanation:

First sentence: Why this is the first line? This paragraph is the first sentence because it asks a question that introduces the main topic. It does not need other sentences for context. It sets up the theme of the text. Why other lines are not chosen? The other paragraphs do not qualify as the first sentence. For example, Paragraph 2 starts with 'Our', which is a pronoun. Paragraph 3 is a question, but it does not introduce the topic. Paragraph 4 starts with 'With', which is a conjunction.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it wraps up the text. It gives a final thought about the excitement of the major. It does not introduce new ideas.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 follows Paragraph 1 because it answers the question from Paragraph 1. It gives information about the Applied Computer Science major. This shows a logical order.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about the problems that the major helps to solve. This shows a cause and effect relationship.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 follows Paragraph 3 because it gives a conclusion about the excitement of discovering new problems. This shows a logical order.