Which of the following are considered as threats to external validity?
According to Campbell and Stanley (1963).
A. Interactive effects of testing
B. Statistical regression
C. Interaction of selection bias and experimental treatment
D. Instrumentation process
E. Reactive effects of experimental arrangement
Choose the correct answer from the options given below:

Correct option is B

External validity refers to the extent to which the results of an experiment can be generalized to other situations, settings, or populations beyond the specific conditions of the study. According to Campbell and Stanley (1963), the following are threats to external validity:
A. Interactive effects of testing: This occurs when the pre-test affects how participants respond to the treatment or post-test. For example, a test before the intervention may make participants more aware of the subject matter, altering their behavior or reactions, which can reduce the ability to generalize the findings to populations who did not undergo the pre-test.
C. Interaction of selection bias and experimental treatment: This refers to the situation where a sample is not representative of the broader population, and the interaction between the selection of participants and the experimental treatment affects the generalizability of the results. For example, if the experimental group is selected based on certain characteristics that don't reflect the larger population, the findings may not apply to other groups.
E. Reactive effects of experimental arrangement: This refers to how participants' behavior can change simply because they are part of an experiment (known as the Hawthorne effect), which can lead to results that do not generalize well to non-experimental settings. The experimental arrangement itself can influence participants' behavior in ways that may not reflect how they would act outside of the study.