Who reviews laws to decide whether it is within the guidelines of the constitution?

The Supreme Court

Explanation:

The Supreme Court is the highest court in the federal judiciary of the United States. One of the most important tasks of the Supreme Court is to review laws in order to establish whether they are within the guidelines of the Constitution. Therefore, the Court has the ability to invalidate a statute if it violates the Constitution. It can also strike down presidential directives for this reason.

i would say b. research typically uses a variety of sources

world war i had a devastating effect on german-americans and their cultural heritage. up until that point   german-americans, as a group, had been spared much of the discrimination, abuse, rejection, collective mistrust experienced by so many different racial and ethnic groups in the history of the united states. indeed, over the years, they had been viewed as a well integrated and esteemed part of american society. all of this change with the outbreak of war.