What Was a Later Critique or Explanation of the Events

What was a later critique or explanation of the events of the Stanford Prison Study?

A) Participants were influenced by the active participation of the principal investigator
B) Participants were influenced by the active participation of the principal investigator.
C) Participants' roles in the study overwhelmed their individuality.
D) Participants were too immature for the study,since prison guards in the United States must be at least 25 years of age.