The Major Fault in the Non-Equivalent Posttest Only Design Is

The major fault in the non-equivalent posttest only design is that

A) it involves random assignment to groups, therefore the groups are not equivalent at the start of the study.
B) the two groups are may not be equivalent at the beginning.
C) there is no way to tell the direction of effect that the independent variable may have.
D) the two groups do not experience the same level of the independent variable.