Participants for a Treatment Group Are Chosen Because They Score

Multiple Choice

Participants for a treatment group are chosen because they score very low on a pretest measure of performance.When their performance improves on the posttest,the researcher

A) should consider the possibility that statistical regression influenced posttest scores.
B) can rule out testing and instrumentation threats to internal validity.
C) can be confident that the treatment was effective.
D) must conclude that additive effects with selection are responsible for the outcome.