The correct option is C history
Option A: It is mentioned in the lines "they should begin to understand a little of one another's historical experience and resulting mentality". This means that one's history results in one's mentality. Hence A is the correct option.
Option B: The phrase 'international position' isn't mentioned in the passage.
Option C: It is not the politics that result in the nation's mentality, but the social and political conditions from historical times.
Option D: The historical experience, and not the present character, determines a nation's mentality.
Hence B, C and D are incorrect.