Final answer:
An example of a fad is d. platform shoes, which were highly popular for a brief period, unlike more timeless styles such as button down shirts or straight leg pants. Fads are a type of collective behavior influenced by the desire to comply with social norms and trends.
Step-by-step explanation:
An example of a fad is d. platform shoes. The other options listed, such as button down shirts, V-neck sweaters, and straight leg pants, tend to be more classic styles that have proven to be largely timeless in their appeal. In contrast, platform shoes are an example of fashion that became extremely popular in a short and intense period, particularly during the 1970s, but their popularity was not sustained over time, which is characteristic of a fad.
Fads are part of collective behavior, where people in a society collectively show a preference for certain behaviors or styles. This type of behavior is influenced by social norms and the desire to feel included or to be seen as trendy. For example, teenagers might follow clothing fads as a way of fitting in, which is not necessarily about saving money or following parents' rules, as referenced in relation to buying clothes.