If Erika's teammates so happened to give her a lot of reasons to go along with their plan, then the implicit message (or the underlying meaning; 'read-between-the-lines- message) would be that Erika should agree too it because it is a good plan that they were proposing.
Dramatic irony means that (B) the audience knows something the character and characters don't.
This style of writing was often used in Greek literature. Readers can interpret the significance of the characters actions and words, something that the character himself or herself cannot.
