Jane: Television programs and movies that depict violence among teenagers are extremely popular.
Conclusion (Hence)
Depictions of violence among teenagers should be prohibited from movies and television programs, if only in those programs and movies promoted to young audiences.
Intermed. Conc. (we have good reason)
Depictions of violence cause young people to engage in violent behavior.
Evidence
TV programs and movies that depict violence among teenagers are extremely popular. These media are influential.
Evaluate
The author has established that shows and movies depicting violence are popular and influential, but she hasn't given any solid support for the notion that they're influential in the sense of .
So one way to strengthen Jane's argument would be to provide some evidence that watching violent shows and movies makes teens more likely to engage in violent behavior, or that .
The conclusion also makes an interesting caveat, saying that at the very least we should prohibit teen-violence from shows and movies promoted to young audiences.
Jane seems to be assuming that shows and movies promoted to young audiences are more likely to be seen by young audiences.
If we were arguing the anti-conclusion, we might say, We might also say,
Goal
Look for anything helping to bolster the connection between teens watching depictions of teen violence and teens engaging in violent behavior, or look for an answer ruling out some potential objection to the idea of prohibiting teen violence from movies and TV aimed at young audiences.