How is the audience's job different in determining an implicit theme rather than an explicit theme?

AWith an explicit theme, the audience has to differentiate between moral and illicit behavior in the characters.

BWith an implicit theme, the audience needs to understand more about the history of English drama.

CWith an implicit theme, the audience has to watch carefully and make inferences based on what the characters do and say.

DWith an explicit theme, the audience sits on all sides of a stage and watches the action from different perspectives.