Question

what other evidence supports the inference about twentieth-century fads?
evidence
students tried to set records for how many people could fit in a phone booth.
evidence
teams of students competed to push hospital beds around a course.
evidence
?
inference
many strange fads in the twentieth century involved competitions.
some people helped raise money for charity.
people in need benefited from many fads.
young people participated in dance marathons.
bizarre fads were popular before the internet.

Explanation:

To support the inference that many 20th - century fads involved competitions, we need to find an option that shows a fad with a competitive element. "Young people participated in dance marathons" is a competitive activity (marathons imply a competitive, timed or effort - based event), so it supports the inference. The other options: "Some people helped raise money for charity" is about charity, not competition; "People in need benefited from many fads" is about the benefit of fads, not competition; "Bizarre fads were popular before the Internet" is about the time of popularity, not competition.

Answer:

Young people participated in dance marathons