Kenneth and mamie clark used sociological research to show that segregation was:
beneficial
harmful
illegal
of no importance

The answer is: Keneth and Mamie Clark used sociological research to show that segregation was harmful.

Explanation:

The research  that Keneth and Mamie Clarck conducted, aimed to know the effects that segregation and race had children's lives. With the use of black and white dolls, and a series of questions asked to African-American children they demonstrated that children not only were aware of segregation, but they had internilzed it at a point were they identified their skin colors with attributes such as bad and ugly.

Although the research recieved many critics regarding methodology and reliability of the results, it also opened the discussion of legal segregation methods such as black schools.

answer; all of the answers are correct;