What modern issue is challenging the concept of federalism in the united states
a. no child left behind act
b. internal revenue laws
c. war in iraq
d. national elections

The modern issue that is challenging the concept of federalism in the United States is the No Child Left Behind act. The correct option among all the options given in the question is option "a". It is an undeniable fact that more children's go to school in Japan than in the United states of America. This is a grave issue as far as the concept of federalism is concerned.

The answer to that would be prussia which would later be germany