First sentence: Why this is the first line? This paragraph is the first sentence because it introduces the main topic. It talks about a problem that people face in rural areas. This is a broad overview of the situation. It does not use any pronouns or definite articles that need prior context. Why other lines are not chosen? Paragraph 2 starts with "In addition to" which is a conjunction, so it cannot be first. Paragraph 3 starts with "Therefore" which is also a conjunction. Paragraph 4 starts with "One such example" which refers to something not yet mentioned, so it cannot be first.

Concluding sentence: Why this is the last line? This paragraph is the last sentence because it gives an example of a solution. It wraps up the discussion by showing a way to solve the problem of lighting homes.

Paragraph pairs:

• Pair 1 (Paragraph 1 → Paragraph 2): Paragraph 2 connects with Paragraph 1 because it explains a problem related to kerosene lamps. The word "these" refers back to kerosene lamps. This is the Noun Pronoun Rule.
• Pair 2 (Paragraph 2 → Paragraph 3): Paragraph 3 connects with Paragraph 2 because it shows a response to the problems mentioned. The word "therefore" shows a cause and effect relationship.
• Pair 3 (Paragraph 3 → Paragraph 4): Paragraph 4 connects with Paragraph 3 because it gives an example of an alternative. The phrase "one such example" shows that it is specific to the alternatives mentioned.