The topic sentence is C. Disunity among people of color due to the exploitation of differences is an inherent part of the system of racism.
The sentences follow a logical order in which the topic sentence introduces the main idea of the paragraph and the other sentences provide further explanation and support. The paragraph discusses the role of racism in creating disunity among people of color, but also acknowledges the potential for unity and emphasizes the need for trust and cooperation to overcome this disunity.