The most likely effect of gentrification for older adults is:
b. A significant reduction in low-cost housing
Gentrification often leads to an increase in property values and rents in certain neighborhoods, which can displace long-term residents, including older adults, who may rely on affordable housing options. While there may be some benefits, such as improved services, the core challenge is often the reduction of affordable housing options for those on fixed incomes, including many seniors.