Anton and his friends are discussing a study he read about in his developmental psychology class. In the study, the researcher made the claim that a majority of middle school students who are bullied have low self-esteem. Clarissa questions the study, saying, "I am not sure that I am convinced—I am not sure you can really measure being bullied." Quinn also questions the study, saying, "Which middle school students did they study? I am curious if they included both private and public school students." Manish also is curious about the study, asking, "I wonder how strong the relationship is between bullying and self-esteem. Could you predict one from the other?"

Manish’s concern is addressing which of the following?

a. The study’s external validity
b. The study’s construct validity
c. The study’s internal validity
d. The study’s statistical validity