The correct answer is C. a parent who guilts his children into visiting him.
Rhetorical devices, pathos, ethos, and logos, are used to achieve some kind of a goal: pathos is used to elicit emotions, ethos to appeal to somebody's morals, and logos to their logic. When a parent uses his words to make his children come and visit him, he is using pathos - strong emotions to try and make them feel sorry for him so that they would see him.
The other options aren't really using any rhetorical device, but C definitely is.