He work of W. E. B. Du Bois, an African American, .
a. was recognized as an important part of the foundations of sociology from the earliest times
b. has been completely ignored until the present
c. was rejected by the National Association for the Advancement of Colored People (NAACP)
d. is recognized as important by contemporary sociologists

Ifound the exercise on the internet. attached is the list mentioned above.in order for a compound to be considered optically active it can't have any axis or plan of symmetry. the molecule  shouldn't also  be superimposable on its mirror image.with such considerations, the compounds that are optically active are: -third compound on the first image is optically active; -second and third compound from the second image are optically actives.