One of your neighbors has many investments in the stock market. They watch the market daily and do a lot of research on companies they may want to invest in and have knowledge about undervalued stocks primed for growth. They have helped several neighbors make investment decisions for their 402k accounts. They have been pleased with the choices, so you ask your neighbor for help, too. In this case, your neighbor could best be categorized as a(n)______
a. reference group
b. opinion leader
c. market maven
d. influencer