Concept:A meaningful paragraph must follow a logical cause-and-effect sequence. Start with the main cause, then add related points, and end with the final outcome.
Explanation:Sentence 4 introduces the first key factor: military weakness.
Sentence 1 adds the economic factor using the word "also".
Sentence 3 shifts to internal political instability.
Sentence 2 provides a specific 19th‑century cause: rising nationalism.
Sentence 5 ends with the final blow – World War I.
This order creates a smooth flow from internal to external causes, leading to collapse.
Answer:Option D:
4−1−3−2−5