An older adult portrayed as a positive role model is not an example of ageism. So the correct option among all the options that are given in the question is option "b". Ageism is actually a social attitude that defines the way people look at older people and stereotypes them as lazy, useless, strong or in any other way. Ageism is also a part of the way where people feel that they can treat any elderly people in demeaning ways.