Even When Pretest Scores Are the Same,on Average,for Treatment and Comparison

Multiple Choice

Even when pretest scores are the same,on average,for treatment and comparison groups in a nonequivalent control group design,the two groups may not be equivalent because

A) the pretest measure is unlikely to be relevant to the dependent variable.
B) the fact that the two groups are equal on the pretest measure does not ensure that the groups are equivalent on other characteristics relevant to the study.
C) the posttest measure is unlikely to be the same as the pretest measure,and the two groups must be equivalent at the posttest.
D) the natural growth rates of two groups from different populations are likely to be the same,but the pretest estimate of equality may still be in error.