The Main Internal Validity Problem of the Static-Group Comparison Design

Multiple Choice

The main internal validity problem of the static-group comparison design is

A) observed posttest differences may be due to preexperimental differences between the groups rather than to the experimental treatment.
B) the interaction between the experimental and control treatments.
C) the pretest may sensitize subjects to the experimental treatment.
D) the matching procedure may result in the loss of too many subjects and thus introduce bias.