Answer:
Maturation
Step-by-step explanation:
Maturation can be described as one of the threats to internal validity whereby participants tend to change over time, this can be clearly observed in the sudden change in the life of students as they transition from high school to college, the student become adjusted to college life.
The self awareness that prompts a change of behaviour as on leaves an environment to another.
Anne finding that there were differences between pre and posttesting is most likely going to cause a change in how she respond to the difference.
Hence, Maturation validity threat.