Regarding Experiments That Use Two Pre-Existing Groups, Which One of the Following

Multiple Choice

Regarding experiments that use two pre-existing groups, which one of the following statements is INCORRECT?

A) If the pre-existing groups were not formed at random, the study is a quasi-experiment.
B) If a pre-existing single group is used, with the treatments alternated on different weeks at random, this is a true experiment.
C) For pre-existing groups, a pre-test is needed to compare their similarity.
D) If two pre-existing groups in a quasi-experiment are highly dissimilar initially, it would be hard to interpret the results of the experiment.