Answer:
A) a history effect.
Step-by-step explanation:
History effect: In psychological research, the term "history effect" is described as different events that generally occurs in the specific environment which is responsible for changing the pre-existing conditions of a particular study, therefore affecting or hindering its outcome. However, these history events can occur either between post-test &pre-test or before starting a specific experiment.
In the question above, the given statement signifies a history effect.