Consider the following:
We "identify" with someone or something when we see ourselves as being linked to it. Why would Asagai see himself as personally linked to the future of his country while Beneatha would not see herself as having much of a role in America's future?
We become invested in change when we believe that we ourselves can affect it (make it happen). Why would Asagai feel like he can make change happen in his country while Beneatha would not feel like she could affect change in the US?
Consider the idea of "minority groups". As a male, Asagai is part of at least one majority group in his country in terms of power. As a black female, Beneatha is part of two minority groups. How might this affect her beliefs about her influence in the US's future?