Liang: Watching movies in which violence is portrayed as an appropriate way to resolve problems increases levels of aggression in viewers. Therefore, children’s access to these movies should be restricted. Sarah: Watching a drama whose characters are violent allows the audience to vicariously experience the emotions associated with aggression and thus be purged of them. Hence, the access by mature audiences to such forms of entertainment should not be restricted.
The dialogue provides the most support for inferring that Liang and Sarah agree with each other that
There is a common understanding between the two that there is some effect on the audience. Now they are talking about different segments and their conclusions differ.
(A) people who experience an emotion vicariously are likely to purge themselves of that emotion - Neither supports this. Even in Sarah's case. Her argument is subjunctive, meaning she is saying what they should do and not they are likely to purge themselves. They may or may not. For example "the principal demanded that students be dressed in the school uniform." But demand doesn't mean that some may not be in uniform. They may be in the uniform or may not not be. Thus, "are likely to purge" is wrong.
(B) the members of a mature audience are unlikely to believe that violence is sometimes an appropriate way to resolve problems - No. Again, Liang doesn't even talk about adults so this is straightforward out. Moreover, even Sarah, says her statement in subjunctive. Likely or unlikely to believe is out of scope. We don't even know from the argument what mature audience believe.
(C) if violence in certain movies causes violence in viewers, access to those movies should be restricted - No. Sarah is opposite.
(D) the effects of dramatic depictions of violence on audiences are at least partially understood - Yes. They agree that there is some psychological effect "at least partially understood." But they disagree on those effects. One demands it should be avoided and other that it should not be avoided.
(E) children are more likely than adults to be attracted to dramas involving characters who behave violently - this comparison is out of scope and not even part of the argument.