The Threat to the Internal Validity of Experiments That Is

The threat to the internal validity of experiments that is called "maturation" is best defined as:

A) changes occurring within experimental subjects that are due to the passage of time.
B) subjects becoming familiar with measuring devices used in experiments after they have been administered repeatedly.
C) the tendency for extremely mature experimental subjects to regress toward the mean of the group over time.
D) historical changes that occur between administration of the pretest and the posttest.