Final answer:
Opinion leaders are defined by their enduring involvement in a product or activity, their expertise, and the trust and influence they hold, rather than by their age, income, or education level.
Step-by-step explanation:
Opinion leaders are characterized by their enduring involvement in the product or activity. They are key figures within certain domains of expertise and interest who influence others' attitudes and behaviors. These influencers are not defined by their age, educational level, or income strictly, although these factors can contribute to the reach and impact an opinion leader may have. For instance, a well-educated individual or someone with a higher income may have more access to platforms that allow for greater influence. However, what distinguishes opinion leaders the most is their recognized expertise, credibility, and the trust they build with their audience, facilitating the spread of opinions and information horizontally within their social strata.