Final answer:
The author develops the idea of peaceful international relationships by explaining a. the changing role of the United Nations and highlighting the importance of learning from past mistakes and conflicts.
Step-by-step explanation:
The author develops the idea of peaceful international relationships by explaining a. the changing role of the United Nations.
The United Nations was founded in 1945 with the purpose of preventing armed conflicts and promoting peaceful policies around the world.
The author also emphasizes the importance of learning from past mistakes and conflicts to create a better future.