Which of the following are threats to internal validity of the single-group before after design?

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All of the above options (A: Retesting threats, B: Attrition threats, C: Maturation threats) are threats to the internal validity of a single-group before-after design. Retesting threats occur when the pretest influences the posttest scores. Attrition threats arise when participants drop out of the study, potentially leaving a non-representative sample. Maturation threats involve changes in participants over time that are unrelated to the intervention.

Which of the Following Are Threats to Internal Validity of the Single-Group