Which of the following is not a threat to internal validity of a study A. subject mortality B. predictive validity C. history D. maturation

B. Predictive validity is not a threat to internal validity of a study. Predictive validity is a type of validity that is used to determine the effectiveness of a study or model in predicting future outcomes. It is not a factor that threatens internal validity, which is concerned with the structure of the study itself and whether it accurately measures what it intends to measure. The other options, subject mortality, history, and maturation, are all potential threats to internal validity. Subject mortality refers to the loss of subjects during the course of a study, history refers to events occurring during the study that could affect the outcome, and maturation refers to changes in subjects over time that could affect the study results.