A.I. Explanation:

Option 1: "international position"

Explanation: The term 'international position' is not explicitly mentioned in the text. The text discusses the need for understanding between nations but does not focus on their international standings or positions. Therefore, this option does not align with the main idea presented.

Option 2: "politics"

Explanation: While the text mentions political reactions, it does not define the mentality and character of the nation solely in terms of politics. The focus is more on understanding historical experiences rather than just political aspects, making this option too narrow.

Option 3: "history"

Explanation: The text emphasizes the importance of understanding one another's historical experiences as a means to diminish ignorance. This directly relates to the mentality and character of nations, as historical context shapes how nations perceive and react to each other.

Option 4: "gross ignorance"

Explanation: Although 'gross ignorance' is mentioned in the text, it describes a problem rather than the mentality and character of a nation. This option does not address the core question about the resulting mentality and character.

Option 5: "socio-political conditions"

Explanation: The text implies that understanding historical experiences and the resulting mentality involves socio-political conditions. These conditions shape how nations interact and perceive each other, making this option relevant to the mentality and character discussed.

Option 6: "cultural heritage"

Explanation: The text does not specifically mention 'cultural heritage' as a factor in understanding the mentality and character of nations. While culture is important, the focus here is on historical experiences and socio-political conditions, making this option less relevant.