Answer: C. On the other hand.
Explanation: in literature, a contrast is the description of the differences between two or more entities, that can be characters, places, events, etc. In the given passage, we can see a contrast between the feelings of Greta and Fred when returning home, Fred is glad and looking forward to see his old friends, but Greta didn't want to see her old boyfriend and already missed New York City, the phrase that helps make this contrast is "on the other hand."
