Final answer:
The most valid criticism of diversity training is that it has not been sufficiently evaluated to determine its effectiveness, which is important in ensuring it serves its purpose without perpetuating stereotypes.
Step-by-step explanation:
Of the criticisms listed for diversity training, the most valid might be that it has not been sufficiently evaluated scientifically to see whether it actually makes an impact. This criticism aligns with the concerns that many interventions, including those aimed at addressing cultural differences in workplaces, are implemented without rigorous scientific evaluation to assess their effectiveness. Diversity training aims to educate participants about cultural differences and improve teamwork, but without proper evaluation, it is difficult to determine if the training achieves its goals or just perpetuates stereotypes.