In the Context of Threats to Internal Validity, History Refers

In the context of threats to internal validity, history refers to:

A) the time between pretest and posttest results that may affect the results of a study.
B) an event that occurs during the administration of a treatment and that may affect a researcher's observations.
C) the differences between groups that exist before the implementation of a treatment and that may indirectly affect the conclusion drawn by the researcher.
D) a developmental change in participants between the pretest and the posttest that might affect the results.