Argument Breakdown:
Premise 1: Nations that have little interaction with one another have little knowledge of one another's needs and problems.
Premise 2: Sympathy and justice depend largely on understanding the needs and problems of others.
Conclusion: The conclusion should logically follow from the premises.
We can say that if nations have little interaction, they lack knowledge of each other's needs and problems.
Since sympathy and justice depend on understanding these needs and problems, the absence of interaction would lead to difficulties in extending sympathy and justice.
(A) nations that have knowledge of one another's needs and problems will treat each other with sympathy and justiceThis option implies that knowledge will definitely lead to sympathy and justice. However, the passage only states that sympathy and justice depend largely on understanding, not that they will definitely occur.
This is a stronger conclusion than the argument supports.(B) without some interaction, nations are bound to find it difficult to extend sympathy and justice to one another
This is consistent with the argument. If interaction is necessary for understanding, and understanding is necessary for sympathy and justice, then lack of interaction would indeed make it difficult for nations to extend sympathy and justice.
(C) almost all problems between nations stem from lack of sympathy and justiceThis choice is too broad. The argument does not claim that most problems stem from a lack of sympathy and justice.
(D) there is no way to eliminate conflict among nations
This is irrelevant to the argument. The argument does not address the elimination of conflict, only the relationship between interaction, knowledge, and the extension of sympathy and justice.
(E) only nations that have some interaction with one another have knowledge of one another's needs and problems
This restates a premise rather than logically completing the argument. It's a necessary part of the argument but doesn't complete the logical progression.
The most logical completion of the argument is (B) without some interaction, nations are bound to find it difficult to extend sympathy and justice to one another. This option directly follows from the premises given and correctly concludes the argument.