I'm not a fan of assuming that because it's in the 17th century then it's unlikely the actor would have a written copy. The printing press was already widespread, so why wouldn't there be written material? I see no reason to believe it'd be rare enough that an actor can't find a copy, even if it's one document traveling with a troupe. You might as well say it's a massive assumption that the actor can read.

C is still the most strongly supported answer because the actor would know the one speech by heart whereas you can assume the audience member, even focusing on this one speech, wouldn't know it as well - and there's no reason to assume they'd know it any better than the rest of the play.