A Researcher Is Least Likely to Encounter Legal Liability in Which

A researcher is least likely to encounter legal liability in which of the following situations?

A) in an observational study you see juveniles spray-painting walls at their school and you say nothing
B) you watch one of your subject deal drugs on the corner and you alert him when a police car turns the corner
C) one of your subjects tells you he committed a rape and you do not tell anyone even though you know what he told you is true
D) you refuse to reveal confidential information under a claim of immunity