Final answer:
The most influential individuals in changing group norms within a group are called opinion leaders. Opinion leaders hold a prominent role in shaping opinions within their social networks and can be from any social stratum.
Step-by-step explanation:
The members of a group who are the most influential in changing group norms are known as opinion leaders. Opinion leaders can be people with official positions, such as bankers or mayors, or individuals within one's immediate social circle. They shape others' opinions either intentionally or unintentionally through their influential role within social networks. These influential individuals are found across all social strata and are key in guiding and shaping public sentiment and behavior within their sphere of influence. While people might think of dignitaries or celebrities as primary opinion leaders, the definition also includes the politically savvy coworker, the neighbor who is well-informed on certain issues, or an active member within a community.
By relating this to the provided context, it is clear that opinion leaders facilitate and occasionally induce changes in group norms, making this the correct terminology for the individuals who are most influential in changing group norms within a social structure.