Which of the Following Threats to External Validity Is an Example

Multiple Choice

Which of the following threats to external validity is an example of the problem of reactive effects of experiment arrangements?

A) A pretest was conducted that sensitized the subjects to the topic of the research, so that they may have responded to the treatment differently than would individuals who did not go through the pretest
B) Defendants in a county court are allowed to choose whether or not they would like to participate in a study to determine the effectiveness of a new diversion program
C) Inmates in a prison are aware that they are part of a study on prison violence and modify their behavior as a result of this awareness
D) Inmates in a prison are participating in two research studies and are simultaneously exposed to two different experimental interventions