Dramatic Irony is when the audience knows something's going to happen, but the characters in the story don't.
The only possible answer could be Option A. The audience knows that these two characters are good friends, but the characters in the story think that they're strangers.
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The text states "Robert needs an education, and so do you, but you can't be educated in the same way." The dad is saying that an education is very important for both of them.