The correct answer is: Only argument II is strong.
Argument I is a weak argument because it is based on the assumption that goodwill always pays dividend. This is not always the case. There are many instances where goodwill has been taken advantage of, and where countries have been harmed by their generosity.
Argument II is a strong argument because it is based on the realistic assessment of the situation. It is true that our generous behavior and goodwill may be considered as our weakness by our erring and nagging neighbors. This could lead them to take advantage of us, and to further their own interests at our expense.
Therefore, only argument II is strong.