How did Latané,Williams,and Harkins,in their classic study of social loafing,distinguish between productivity loss caused by loafing,and loss caused by coordination problems?

A) They studied highly motivated people in one condition,and unmotivated people in another.
B) They led some people to believe they were working in groups when they were alone.
C) They had some people work at collective tasks,whereas others worked on a coaction task.
D) They trained some groups to eliminate coordination problems,but did not train others.
E) They set clear,difficult but attainable goals for some groups,but other groups had no goals.