Answer:
Main subject and action: "many people under the age of 24 are using social media less
What detail tells the source: "a 2019 survey"
Which details tell more about...: "with 61 percent taking a break from it and 33 percent quitting it altogether."
Step-by-step explanation:
If they just asked for the main subject, I would say it was the survey. But since they asked for a subject and action, I chose the answers above. Hope it helps.