First sentence: Why this is the first line? This paragraph is the first because it introduces the main topic of the text, which is the discovery of penicillin. It is a broad overview of the subject matter. It does not use any pronouns or definite articles that refer to previous information. Why other lines are not chosen? Paragraph 2 starts with "This accidental discovery" which uses a pronoun that refers back to the previous sentence, so it is not independent. Paragraph 3 starts with "The development" which uses the definite article "the" and assumes prior knowledge, so it is not independent. Paragraph 4 starts with "Penicillin's success" which also assumes prior knowledge, so it is not independent. Paragraph 5 starts with "Consequently" which is a transitional word, so it is not independent.

Concluding sentence: Why this is the last line? This paragraph is the last because it summarizes the overall impact of antibiotics. It uses the word "Consequently" which indicates a conclusion. It brings together the earlier points about the discovery and success of penicillin and its effects on healthcare.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it gives more details about the discovery mentioned in Paragraph 1. This is a Broader to Specific Strategy, as Paragraph 1 introduces the discovery and Paragraph 2 explains how it happened.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it talks about what happened after the discovery. This is a Logical Order, as it follows the timeline from the discovery to the development and use of penicillin.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it shows the result of penicillin's success. This is a Cause and Effect Relationship, as the success of penicillin led to the creation of more antibiotics.
• Pair 4 (Paragraph 4 → Paragraph 5): Paragraph 5 connects with Paragraph 4 because it explains the impact of the research and creation of more antibiotics. This is a Cause and Effect Relationship, as the success of antibiotics led to a reduction in mortality rates.