Why is it useful for historians to base certain studies on the analysis of historical periods? < br />
a. the major historical themes apply only to certain civilizations during certain periods< br />
b. the ideas that characterize a particular period are unaffected by ideas from other periods< br />
c. similar events and trend often take place on different places during the same periods< br />
d. experience has confirmed the analyzing periods is the most effective approach to history

the answer is a

explanation:

du boi was considered a radical because he wanted the immediate end for segregation. the biggest different between him and booker t. washington is that, even though washington believed that segregation should be considered illegal, he did not believe at all that a law was needed to keep blacks away from whites and that this would be something natural (to have the races apart) for a long time until society adjusted, while du boi believe that agitation was the only way to end segregation.

the colonial period, since this was a time of mass immigration from a variety of people from europe.