Answer & Explanation:
There are several pieces of evidence that support the inference about twentieth-century fads:
Many strange fads in the twentieth century involved competitions1.
People in need benefited from many fads1.
Young people participated in dance marathons12. This was a popular trend of the decade and was a way for young Americans to prove their agility3.
Bizarre fads were popular before the Internet1.
These examples illustrate how fads were not just about following trends, but also about community engagement, helping those in need, and showcasing talents. Please note that the effectiveness and impact of these fads could vary widely.