What was a notable characteristic of the group used in Asch's experiment?

The group used in Asch's experiment is notable primarily because it included confederates who were part of the research design. Confederates are individuals who are in on the experiment and act in a way that influences the behavior of the actual participants. In Asch's studies on conformity, the confederates provided intentionally incorrect answers to certain questions about line lengths to observe how the true participants would react. This setup was crucial for assessing the degree to which social pressure from the group would lead individuals to conform to a majority viewpoint, even when it was clearly incorrect. The presence of confederates was essential to Asch's investigation into group dynamics and the influence of group conformity on individual decision-making.

The other choices do not accurately capture the main aspect of what defined the group in Asch's study. The participants were not all experts in psychology, nor did they necessarily include a balanced mix of genders or come from diverse backgrounds; these factors were not central to the exploration of social conformity that Asch was examining.