Explanation: John’s words are the permission to go ahead, leave the conversation.
Therefore, the interlocutor will also say goodbye.
John: “Oh, it’s great to talk to you, but I have to go quickly.”
Jane: “Ok. See you later”
The remaining answers:
A. Well, another time = Oh, another time
It is polite to say when an invitation is declined.
B. Yes, I enjoyed talking to you, too. = Yes, I also enjoy talking to you. John didn’t ask if Jane liked talking to him, so he couldn’t answer that.
D. That’s nice = That’s great
Is a polite response when you are not interested in what the other person is saying, or are not in the mood to listen.