Which of the Following Is an Example of a System

Which of the following is an example of a system variable that might lead to inaccuracies in eyewitness identifications in lineups?

A) The number of people chosen to appear in the lineup alongside the suspect
B) Whether the eyewitness is confident about his or her identification of the eyewitness during the lineup procedure
C) Whether the eyewitness and the criminal are of the same race/ethnicity
D) Whether the witness is confident about the original statement that he or she gave to the police