Wilson Bases His Examination of Inner-City Black Males on All

Wilson bases his examination of inner-city black males on all of the following research approaches EXCEPT

A) ethnographic research that he and his team of researchers conducted for many years.
B) studies on inner-city black males by other researchers.
C) survey research and data reported in scholarly articles and books.
D) statements from inner-city black males gathered by the U.S. Department of Labor's decennial survey of joblessness and the low-wage job market.